[GAEventer]

Really only at the 4* level. There are a lot of mares at levels below. There are not as many stallions. Perhaps is because both mares and stallions can have more self preservation which can limit them xc....or really, to find a horse that can do the xc and jumping yet still have the rideability for dressage is just plain hard to find.

Actually mares (I don't know about stallions) have less 'sense of self preservation' than geldings. A good mare will give you all she has until she gives out. 90+% of polo ponies are mares; they are chosen over geldings because they won't give up like a gelding will.
I've ridden quite a few mares and have always felt that they were more careful and conscious of their rider than the boys.

[bornfreenowexpensive]

I've ridden quite a few mares and have always felt that they were more careful and conscious of their rider than the boys.

That is what I meant on self preservation. They are not going to jump off a cliff with their rider. When they see the combination is bad, they often (not always) have the self preservation and awareness of their body to make a safe judgement call. But they have the heart to give their all. When you have a connection with a good mare...they will give you 110% and have that competitive drive like nothing else.