Many are quite purdy indeed . I wish I had your avatar skill!

These are more suited to icons for a journal, seeing as they are so big. Are you incapable of designing something smaller and more common on fora?
More common? I just double checked some of the forums I commonly visited in the last 72 or so hours and 8 out of 11 would allow these avatars. The three that didn't would be EoFF, tGA, and a forum that didn't allow allow anything with animations[otherwise they were acceptable]. Note: I only bothered checking forums where you could actually set a custom avatar(rather than just one from a gallery, some of them may have smaller limits, but it doesn't matter regardless).

Could be different circles, but in my experience forums like EoFF are in the minority.

The swinging sheep probably could use more frames for motion,
I concur with this. However, making it smooth AND small is probably not an easy task. You do a very very good job of making animated avatars that are small in file size. Most of them I end up seeing outside of your work are huge things!