These are my opinions at the moment, I'm noting them for future reference to see if my mind changes.
Four-part settings of Byzantine music just don't work. Especially when they add a lot of weird stuff in the non-melody parts. If you want Byzantine, just do Byzantine.
If you do have a Byzantine-ish setting, please have an ison or something marked. It makes things sound better.
Mixing "normal" Byzantine music and "normal" 4-part Russian music just doesn't - at least not generally - work. Pick one and roll with it. Maybe other polyphonic stuff can mix with Russian stuff, but the contrast of those two styles is just too great.
It would be really nice to have a tenor. And a guarantee of one extra person on every other part. At the moment, we generally have a soprano/melody, have a bass when I'm there, and usually have an alto. Things rapidly get complicated when people disappear. At least, I presume from seeing what it's like when other people aren't here. I don't know what it's like when I'm not here.
I appreciate the need for well-assembled music books. I prefer books assembled in "modular" fashion rather than with everything integrated. If done well, that makes it easier to switch things out if necessary.
It would be nice to be able to change some of the music occasionally - or permanently. But I do appreciate how the previous points make change difficult. The ideal, of course, is to do everything I know how to do already, especially the pieces I like, and maybe a few new things, and to do it all in the way in which I am familiar with doing them.
EDIT: Another note is that, generally, the singing has always been a problem for "other people" to me in the past. If I had known, I suppose, that I would have needed to do something with it in the future, I might have paid more attention to the music. A lot of these pieces I know, but had never even seen until last year. The exception is some vespers and matins music.