I know that some OO are not comfortable entertaining this thought because of their highly ecumencial inclinations (which I do not condemn, but it becomes problematic when they cannot entertain the thoughts of those who do not share those inclinations), but I must address it because they are truly my thoughts. Perhaps unlike you, I am not so confident of the pure orthodoxy of the EO Tradition, and thus I am likewise not confident that the EO clergy have the fullness Apostolic Succession. I am thus not really comfortable submitting myself to an EO priest in such an absolute manner as you are speaking of while I consider the EO Tradition to probably include a strand of Christology that is crypto-Nestorian.
I can imagine your frustration. Here you are, trying to convert from the EO Church to the OO Church, and the OO's, instead of cheering, are telling you to think it through first. I mean what kind of Church does that with potential converts? One would think we should be shouting: "Great! You're leaving those heretic EO's and coming to the True Church! Welcome home! You are truly saved now." Instead, what you are hearing is, "But you are already Orthodox," and "Think it over." We OO's are a funny bunch. But let me explain.

Have you ever noticed that in the OO Church there is a whole lot of diversity in practice and that it really doesn't bother us at all? For example, we have very different liturgies. We also have different calendars. Some of us are on the new calendar and some are on the old. Some of us do Easter when the Catholics do, and some do it at the traditional time. I think there are also some different practices when it comes to how we all cross ourselves. And yet, none of this bothers us. The Copts are not bothered by the fact that the Armenians use unleavened bread and the Armenians don't care that the Copts use a communion spoon. Even the shapes of our altars are different, and absolutely nobody gets excited about it.
Contrast that with the EO Church where there is a lot more uniformity. I attribute that to the fact that they had an empire and that in an empire there is a "my way or the highway" mentality on the part of emperors who feel more secure when everyone is just like they are. I could be wrong about this. I am certainly no historian. It could be they all became this uniform by accident, but that would be weird.
One big benefit from having the uniformity is that a Greek can visit a Russian church and know exactly what is going on during the liturgy. That's definitely a cool thing. I mean, I've been to two Ethiopian liturgies in my life, and while they were breathtakingly beautiful, I had a hard time understanding what was going on.
There are some benefits, however, to having more diversity in the OO Church. One benefit is that in keeping all our ancient liturgies as they are and not making them conform to a certain model, we've preserved a lot of very ancient Christian practices that have been lost elsewhere in the world. Another benefit is that tolerating diversity has kept us from having as many schisms as our EO brothers have unfortunately had. That second benefit, in my opinion, is very important.
One thing that I have noticed since being on OCnet is that the EO's tend to feel that any deviation from how they do things must be associated with heresy. Hence all the schisms associated with calendars, how to cross oneself, etc.
We OO's, on the other hand, look at the underlying faith, rather than the externals. Again and again, I and other OO's have answered questions from EO's who can't understand why the Copts, Syrians, Indians and Ethiopians will commune with the Armenians when the Armenians use unleavened bread. It just doesn't make sense to them that we should be in communion with each other when there is that kind of difference between us. We always explain to them that this is because we look at the underlying faith that is between us, so it doesn't matter. EO's seem genuinely perplexed by this.
OK, I've been rambling, and where am I going with all this? Oh yeah.
This tendency to look at the underlying faith, rather than the externals, is, in my opinion, why you find the OO's to be more ecumenically minded toward the EO's, than the other way around. Something you will see on OCnet, for example, is that there are more EO's calling the OO's heretics than the other way around. Not that all the EO's here feel that way toward the OO's. Also, we've had at least one OO who was quite uncompromising in his belief that EO's are heretics.
It's just that it is more common to see an EO assume that the difference in Christological language must mean that the other side holds wildly heretical beliefs. The OO's on the other hand are more likely to look instead at what the other side
means when they use their language, rather than just focusing on the language itself.
Anyway, to finally bring this all to your situation, I think the problem here is that you are trying to come to the OO, with a mindset that I would call an EO mindset. You are looking at the language that the EO's use and it bothers you that some of the language they use is language traditionally embraced by Nestorians. The history surrounding Chalcedon is also bothersome. However, you need to realize that we OO's are concerned with what our EO brothers today
actually believe. To us, what they actually mean today when they say "two natures," is more important than what their language could possibly be interpreted to mean, or whether the Church of the East also uses it, or whether back in the fifth century some people who embraced Chalcedon were Nestorian, or whatever.
Now it could be that in your particular community, there are some people who are giving an extreme interpretation to the "two nature" language and are making it seem like Christ really was operating as two separate beings. I don't know. Now and then, during the course of heated polemics, we've seen one or two EO's here at OCnet say extreme things that would be very inconsistent with their own fifth council. I question, however, whether it would really be fair to take that and say it means today's EO Church is crypto-Nestorian.
Anyway, if you really are serious about being OO, you need to first look at the EO tradition you are about to leave with an OO mindset. You need to step away from looking at the external language and ask what the EO Church
means when it says "two natures." Forget that some of their language is shared by the Church of the East. Forget that Nestorius liked the Tome of Leo. Put aside for a moment the horrible history. Just look at what the EO Church
actually believes.
When you are able to do that, you'll be able to see why so many of us are telling you that you are already Orthodox and that you need to really think this through. If after doing this, you still want to convert, that's fine. There are plenty of reasons to convert to the OO Church. For starters, our food is way better.

However, if you convert because you believe the EO Church is crypto-Nestorian, you'll continue to be frustrated as you will be using a mindset different from other OO's and you'll be surrounded by people who disagree with your feelings toward your former Church.
Just my extremely long and rambling 2 cents. I just hope this helps you understand us better.
