Frame Question

On my trials I have a sloped frame like the Pashley and United ones, what are the advantages to have one that is squared off on the top, I don’t know if mine is a Pashley or United, and are there any advantages to the curved ones, thanks.

The top part is called the crown, the advantage is you have a place to put your foot, for one footed tricks, and transitions.

my generic unicycle had a frame with a round crown and my onza has a straight one. An advantage for the round frame is that you won’t hit your knees on it. I had bruises all around my knees from my onza because i would do something like a rolling mount and hit my knee really hard against the straight frame.

Here is a thread with a poll about the curved and straight frame.
http://www.unicyclist.com/forums/showthread.php?s=&threadid=33861&highlight=Poll+straight+vs+round+frame