I think another thing that would help set the characters apart--even in character sheets like this--would be to give them poses more indicative of their character. Sabre should stand regally, Whisper should sit gracefully, your villain should hunch aggressively etc. that sort of thing.

Body posture as well as body design go a long way in expressing the character itself.

Look at Balto and how all teh dogs look the same in some regards to the supporting chararcters. But their postures helped to enhance their different personalities. ;)

I like the first and the last one the best. I'm really attracted to the paws and legs. :)