You are right, selective checkout is a good idea. It takes quite some time (especially on slow connections) and space to checkout whole trunk. I'm just not sure how to do that in ebuild, but I hope one of you can figure it out
I used to have two versions of theide as well. But the U++ is so stable now, that I stopped feeling the need for "stable" version
Honza
emerge is smart enough to update, so you only checkout once. Still it couldn't hurt to limit it, I will change it later.
I've been bitten before by development versions, so its always nice to have a fallback
Anyway, I'm in the process of getting the ebuild commited to the sunrise layout, so it will be much easier to emerge and maintain. This will take some time though.