I've seen teh Sabretoothed cats done twice. Once was in a Amazon/Dogs of War Army for Fanatasy and the other was a Squad of Rough Riders for Golden Deamon Australia. It didn't win any awards unfortuantly which I thought it should have since i was very well done, it was just in a montage of pictures.
I think the main reasons people don't go for those as mounts is because there are only two poses, they are metal and very few people know how to paint stripes or spots well enough to look natural. Cold Ones are quiet simple to paint. I'm am seriously considering making a squad of them even though a lot of people do them.