I would recommend keeping an eye on vico. It's likely it doesn't do everything you're used to in vim, but there's been constant improvement in this regard over the past 2-3 months.
Problem with vico is that it's based on textmate plugins. If it natively supported vi (and mvim) plugins, then I would have already purchased it. I never understood the decision to go that direction. Vico is gorgeous, though.
That's both an advantage and a disadvantage in my book. The upside is the scripting language is pretty awesome (in my mind). Presumably it would have taken significantly longer to write full handling for the vi scripting language. TextMate bundles seem to be more limited, except insofar as they invoke external scripts.
I do get what you're saying though. You lose a great deal of existing work because of that. I considered vico a new editor built on the base concept of vim, rather than a total replacement, and in that sense I think it succeeds very well.
