Looking at some of the descriptions of perytons makes me think I should upgrade deer and make a civ for them. What I'll probably do is make them fairly basic and have the civ randomly pick from deer, antelope, goats, and so on, so we can have a neat little trading civ as an extra, though I'll have to do some entity fiddling to solve the current world gen problems. Then when I make the various hippogriff creatures I can make basic "X with the Y of a Z" with entries for every Y and Z, and just go through them all making the pony, deer, griffon, buffalo and whatever else versions with fitting, vague or made up names for each. Might try using animal variations, those are always fun to debug.
I'll probably try to just get the deer/goat/antelope civ working, fix up the pets, do some entity tweaking and some bugfixing for a soonish release, though, since the current issues regarding banana ents are a bit embarrassing and megabeasts will take a while to get just right.
I've never been that fond of butchering sentients. Material values are usually low and they tend to have low stack sizes.