Well Nightfly is. He naturally jumps off one leg although he got great off two feet in time with his maturization, strength training and lowering bodyfat levels. At ~15 years old he had a what, 24 inch two footed vert and now at 22 he has a 42 inch vert off two feet and probably a ~43 off one leg at his maximum, best day.
For me, I have no idea what my 1-leg jump PR is. It kind of varies. It should be around ~36-38 though. I had a moment in the past where I was sick and stayed in bed 3 days, one after another, then as my sickness gone away I went in the park and could barely walk, I was getting tired very very quickly and felt so weak, and then I tried to jump at the rim (just to goof around) and was jumping I think close to 40 inches, I mean WTF?
, and hitting my head in the middle of the net at the 2.96 rim. Right now I can just scrape that net with my head but I don't really have the best jumping technique WITHOUT the ball in my hand at this point in time.
So as you can see, weird stuff usually happens with my one leg jump. It depends a lot on fatigue levels (and as silly that was, I think staying 3 days in bed fully rested my leg muscles although you'd expect to suck hard after such an event) more in the 1-leg jump since there's more overload occuring (there's more speed in the plant than in a two-footed jump) and the overload happens for the muscles of 1 leg so that's another point of excessive overload as well.
And frankly, I think the whole key, besides voluntary strength as expressed in the weight room - is to make your body accept VERY HIGH levels of overload without allowing the leg to collapse under such a high stress. Great eccentric strength levels are needed for a great one leg jump and also, the body position in the plant is very important.
My bodyfat levels have decreased lately, but I think I'm around 13%.