The sharper edge offers less edge-to-head contact area, which allows the head to reverberate longer, hence slightly increased projection and sustain.
It can mean more overtones and sometimes a little bit more work to get them tuned just right, but the extra resonance and overtones will allow for greater flexibility with your tuning.
My force 3007 kit sounds great micd up, but I am running them with 2-ply tom heads at the moment and the head's thicker design kinda makes the sharper edge theory mute. On my Designer series though, the single ply heads absolutely sing, with heaps of low-end.
Some companies deliberately round their edges to give a more focused thump, particularly on floor toms. My theory is that if you ever wanted to ADD resonance to these drums, youd be limited for options. If drums with sharper bearing edges offer too much resonance, its always easier to dampen to your needs...
My 2 cents anyway...