The whole "valid"/"grace bearing" argument as it's now being debated (all too often on the internet) is steeped in superficiality and narrow ways of thinking which I think are out of keeping with the lived, genuinely traditional Orthodoxy of centuries prior to our own. Attempts to revise this, to seek after a "purer" Orthodoxy we can imagine from picking and choosing amongst ancient patristic texts (St.Cyprian of Carthage seems to be a favourite in this regard), is simply a varient of Protestantism. That's not a value judgement, I'm just calling it what it is - and last I checked, Orthodoxy is not Protestant in any sense, rather it is "traditional"; adhering to that which is passed downward in time, with the faith and understanding this transmission is filled with and protected by the grace of the Holy Spirit.
The fact of the matter is that there was a fork in the road between the Greek and Russian Orthdox (local) traditions several centuries ago. The EP (and those who followed him) decided that the baptismal form used by Latins (or those like them, like certain confessional Protestants), because it was pouring (and not full immersion) was invalid. Thus, all converts from Catholicism had to be Baptized.
OTOH, the Russians after their own internal debates, decided the Latin method of Baptism was "valid" - so Baptizing them with immersion was not necessary.
The discussion of GRACE otoh, actually quite separate to this. How the two got mixed up together is a long discussion. Suffice it to say, there are now some Orthodoxy who have confounded the two absolutely. IMHO though, this was not the original discussion - rather the original disagreement, was whether or not pouring water three times could in any way be deemed a valid Baptism.
Grace is the merciful outpouring of God's energies, of Himself, joining us to Him, reforming us, saving us. Frankly, God can do whatever He pleases, though He has revealed what we are supposed to do - whatever may (or may not) occur outside of this, is hidden in Him, and not something any of us can claim to be privy to (and this is where heretical ecumenism falters - it's gross presumption, claiming as a matter of fact where and how God acts outside of His expressed will.)
Obviously the Church, communicates this salvation to those who can receive it. Her Holy Mysteries are genuine, they are sanctified and they sanctify.
As for those who are to varying degrees cleaved from the Church, we really cannot say. While we cannot be blind and pretend signs of grace do not exist where they very well appear to (such as in some Roman Catholic saints) or at least not dismiss them and claim they are really the work of the devil, what we equally cannot do is pretend to know what the extent of this perceived grace is, or it's universality within said sect or schism. Also, even if we could know that such and such persons in such and such schism have grace (which we really cannot), what we can definately say is that their way is not for us; frankly, they do not know better, we do, and while God may smile upon their loving, cheerful ignorance, we will not be forgiven of doing as they do without repenting of it.
This is also why, in principle, I don't see a problem with either approach in regards to converts (Baptizing them or receiving them by the second or third rite, depending where they came from.) The Church can energize a graceless, if valid Baptism, or She can simply repeat the entire thing since it would not be a repetition of the grace of regeneration. Perhaps this is particularly valuable in our day, since the western confessions have so far strayed away from Orthodoxy with their liberalism and theological creativity, that it's not even certain how much but a little water and some words remains in their baptismal ceremonies. It's not even clear if many of these westerners even believe in the Holy Trinity, even if they utter the same words when they pour water three times over the forehead. In this light, the "re"-Baptism of converts would also be covered under ancient canons which rule that when the possible Baptism of someone in the past is doubtful, a Priest should not hesitate to Baptize them, even if it potentially means they are being "re-Baptized". The danger of doing the latter, is far outweighed by the uncertainty involved in not properly initiating them into the Holy Mysteries.