For me, it's a matter of not only apostolic roots (which the major churches have - Catholic, EO, OO, and even the Nestorians via Mar Addai, which is the Syriac name of St. Thaddeus, one of the 70), but of resources. As I mentioned in my previous post, there are a lot of things that seem to be missing from modern RCism as it is practiced, and I know that when I left the RCC my feeling was not "Oh goodness! What a false church I was enticed by!" or anything like that, but "I have gone as far as I can go in this church; I can either stay and starve to death, or leave and try to find some place that is healthier for me." Without all of these things to connect the believer to their faith, the believer is thus impoverished. Often what has replaced these things are various things that, at least from my perspective, are spiritually unhealthy ("sacred heart" theology, various visions/apparitions and esoteric messages based on them, etc.). These are, because of the time that has passed since the abandonment of the original, apostolic faith once practiced by the RCC, taken by most modern RCs to be Catholicism itself. What was there before is forgotten in favor of later developments.
For example, take a listen and look at the Mozarabic rite hymnody, chanted here by Ensemble Organum from the 15th century reconstruction of Fr. Cisneros, who reconstructed the liturgy at that time after it had been suppressed for several centuries in Spain in favor of the imposed Latin rite. (This process of suppression led to the famous "Trial by fire" whereby the Mozarab liturgy book was thrown into the fire, together with the Latin rite liturgy book; the latter burned, but the former would not.)
http://www.youtube.com/watch?v=qqiCs3oL3yg
The art in the above video is also Spanish/Western, of the Romanesque period (10th-13th century or so). Does this hymn and artwork seem more in keeping to everyone here with modern RC spirituality, or Orthodox spirituality? I know my answer, and this is emphatically not an East/West thing (heck, I am a Westerner, too) -- this is entirely within the history and tradition of the RCC. But again, they have abandoned it in favor of other things, much to the detriment of their people and church. And if you ask them (as I have) why they do not have that, they say it is monastic spirituality and so unfair to compare it to the everyday life of an RC parish. Well, why? Why is that? Had these ways of being Catholic not been replaced by later developments, there would not be such a division to be invoked in order to protect the RCC from claims that it has wandered away from the faith. In my own experience in visiting a Benedictine monastery on the Oregon coast before leaving the RCC, I loved it, but it kind of made me mad at the same time. I asked my priest, a Dominican, why it is so hard to find this sort of thing. He replied that "it's out there (traditional, serious Catholic spirituality), but you do have to dig for it in the modern world". Well, why should that be? It shouldn't be. But it is. And the fact that it is speaks volumes, to me.
While I meant that as only an example, it should be said at the same time that some are trying to bring this particular form back. It's good to see, but bad that they should have to, you know?
Praelegendum de la Misa Mozarabe (UBI SUNT?) - YouTube
Long story short, if you don't abandon things in the first place, you won't have to try to recover them later. It's much more difficult later on after centuries of this other stuff being fed to you in place of your authentic tradition(s). I have several Maronite Catholic friends for whom this point is a constant thorn in their sides, sadly.
With this in mind, I have to be honest and say that I cannot see the pull of Catholicism. It seems as though there would be a lot for an Orthodox person to give up in the process, even as I know that the RCC and its people claim that the Eastern Catholic Churches are there to preserve the Orthodox patrimony in all ways, but with communion with the "Chair of Peter". Even disregarding the ecclesiological and historical problems with this claim (e.g., the founding of Antioch by St. Peter as well), that is simply not the case in reality. Witness the differences, for instance, between a Maronite liturgy (the Maronites being West Syriac Christians, by tradition) and a Syriac Orthodox liturgy (also West Syriac).
Maronite Easter liturgy:
http://www.youtube.com/watch?v=TASjGW5YD9A
Syriac Orthodox liturgy:
http://www.youtube.com/watch?v=PFBpORLFnHI
This may or may not be more of a problem for EO switching to their corresponding Catholic church (most of the Eastern Catholic churches are Byzantine, anyway), but my own experience with the Ruthenians tells me that it's something of a gamble there, too. When I visited them, they didn't have an organ or anything, but they also didn't really have a choir, they said the Creed with the filioque included, and didn't really chant the liturgy (which might have been why it was only about an hour). It was very underwhelming, and I can't help but think that it speaks to a certain decline in their traditional spirituality that the people were not up in arms about this, but seemed to think it was normal. I noticed all this stuff on my first visit, and I am not now and have never been Byzantine or any kind of Slavic person.
I know personal anecdotes and YouTube videos can't stand for anything in place of going and seeing yourself, but I would consider the unevenness with which even Eastern Catholics approach their faith to be another strike against this idea that you can even somehow be in communion with a spirituality-impoverished Church like Rome and not have it affect you (this whole "Orthodox in Union with Rome" idea that seems to live on the internet and nowhere else; it's a compromise that satisfies nobody).
Why abandon what you have on the off chance that you might luck out and get a good parish, where the priest knows what he's doing/the historical norms, doesn't put up with Latinizing nonsense, etc. How many of those priests even are there, and why should things be left up to chance like that? It just doesn't make sense to me.
If you take communion as being a sign of shared faith, then you are signing up for every problem that Rome has. In the modern day, those are many (as can be said about all churches, I guess), but more importantly Rome doesn't seem to be serious about doing anything about them, because doing in a real, permanent way would mean going back centuries...and again, they just don't have the structure overall in the same shape as it once was to even be able to do that. They're too degraded after 1400 or 1000 years (depending on what communion you're in
) of doing other things. Lord have mercy.
