You asked many questions, so please forgive the short answers!
(Check my profile for a background on where I'm coming from)
If you are in ROCOR, why are you in ROCOR? What keeps you there?
Because it has the spirit (or savor) of the Church to a greater extent than any jurisdiction in America. ROCOR has, for the most part, kept its conservative, traditionalist Orthodox roots, and because of this it hasn't fallen into the errors that many other groups have (e.g., ecumenism, many modernistic practices such as allowing birth control and communing at heterodox churches, changing the calendar, etc.) ROCOR is not perfect--when one tries to be conservative there is always the danger of being legalistic, closed-minded, and so forth; some fall into these dangers (me included). However, for the most part, ROCOR is the "most salty" of all the jurisdictions in America--and really in the world.
Some see the "russianness" of ROCOR as a bad thing, but it's really just them being consistent. They have always maintained that they are a Church in exile... a Church waiting to return home and again become part of the whole, undivided Church of Russia. We can't expect them to have an "American phase" somewhere in between leaving Russia and reestablishing the Russian Church! As one ROCOR Priest (who later became my spiritual father) told me before I became ROCOR, look for the truth, that's what's important. And so now, this decidedly American guy is happily sojourning in the Russian Orthodox Church Outside of Russia.
Would you attend a non-ROCOR church for services?
I attended an OCA Church for vespers two weeks ago, and my wife and I plan on again visiting the Romanian (OCA) monastery in Ellwood City, PA, sometime soon. So... yes.
Do you believe that the churches under the EP have Grace?
I'd like to think so. I'm not as sure as I used to be. I guess they do. Don't quote me on that.
If you are in ROCOR, how would you react if a friend of yours (in ROCOR) went to the GOA, OCA, etc?
But all my ROCOR friends are going the opposite direction!
For me, it would depend on a number of factors, most importantly whether he had became ROCOR later in his life or not. For someone to have been born into ROCOR and then switch, I guess I would majorly disagree with that move. However, I think it'd be a much worse move were someone to become ROCOR later in life and then decide to leave. Why all the changing? What has changed that they wanted to be ROCOR, and now want to leave? Also, why OCA, GOA, or whatever? If they have some problem with ROCOR, why not another more traditionalist jurisdiction, such as GOC? Or at least a jurisdiction with traditionalist aspects to it, such as the Serbs or Jerusalem? I would also let my friend know that in a few years, he might not like what I'd be saying... if the OCA, GOA, etc. kept going down the path they were on. More importantly, he (I hope!) wouldn't like where he was, and would have to "switch back" yet again.
I would ask them on another site, but this site is the friendliest of them all,
That got me to laugh out loud.
Not that I'm disputing what you're saying. Sort of. Lol.