Usually, the tougher player does punt returns. Because there's so much less room to run, the PR often gets drilled right away. So you generally don't want some wiry guy doing it. Ginn's no good to us if he's broken in half.
I liked what Bess did, and I do think he's tough enough. But I don't want to see him get injured, because I think he's worth too much as a receiver. So I say let Cobbs handle KR and PR duties.
As a side note, keep in mind that, as per the agreement reached at the owners' meeting, the wedge is gonna be illegal from here on out. So that changes the KR game considerably. What we saw last season and in 2007 is probably not even applicable anymore.