Hehe... what a dilemma to be in
I actually started out as top only - I didn't really consider the other possibilities :-) (I know it sounds ridiculous!) And the first times I tried it I found it painful...
But that changed :D
I think you have a point when you hint at people's embarassement - many guys find being bottom "too gay" and some shemales find topping "too manly" :-(