I throw in my usual two cents:
The only two possible breeds are the Suthay and Suthay-raht (note: It's -raht, not -rath. Made the mistake myself often enough
). The Ohmes are much more human like (Ohmes look like Bosmer, Ohmes-raht like lightly furred Bosmer with a tail). Cathay(-raht) are not only described as "jaguar people", but also as considerable larger and stronger than Suthay-raht. We "see" a Cathay-raht variant in the novel "A Dance in the Fire" - there they're mistaken for werewolves from a short distant. Doubt you could say the same about Oblivion's Khajiit.
Now if you look at the Khajiiti forms, there are some "rules" you can see:
1. For feline forms, the -raht variant is considerable bigger.
2. For humanoid forms, the -raht form is a bit bigger, but mostly more cat like.
3. Going with the lunar phases, the feline forms get smaller.
4. Going with the lunar phases, the humanoid forms get more beast like.
Now #1 and #3 can be ignored. #2 and #4 also make it more likely that it can only be the Suthay or Suthay-raht. Now which of them, I doubt we will ever know for sure. Lest a dev says it's this or that form.
I think, following the above, that it's the Suthay, not the Suthay-raht. Oblivion's Khajiit are less beast like than Morrowinds, which would be in tune with the above rules - it's not so much the actual size difference separating the Suthay and Suthay-raht (Oblivion's Khajiit are a little bit smaller, if Morrowind's could stand in the same way - which they cannot, and therefore only appear to be the same height), but it's more about how cat like the individuals are. And both mentally and physically Oblivion's Khajiit are less cat like than Morrowind's. Therefore I have a tendency towards Suthay.
Of course it could also be Suthay-raht, due to dev lazyness, which would be a likely explanation, too. But that would be boring
.
I'd like to see those spots you're talking about though. I didn't see them on my own character but my graphics card chokes on high detail detail and I couldn't see them on any screens either.
I barely dare to say so, but how good they're visible depends a lot on mods. The character textures used in Oblivion are quite bad and low res, and even on "high detail" a lot gets lost. Therefore http://www.tikanderoga.net/bg2408/pics/tes/oblivion_malekhajiitupperbodytexture.jpg. As you can hopefully see, there are spots on the back. However seeing them in game without mods, uh, I don't even want to test it. In game it's, if I recall correctly, just a blurry mush. Unless you use high res textures
.