You're correct about the gather and the ability to cinch up the edges. My preference is the channel for a few reasons; 1) The ball that is created with a channel is (IMO) a more secure method of attaching to whoopies or straps, etc. 2) I've had gathered-end whipping slip - see #1. 3) You can add shock cord in the length of the hammock to take up some of the extra fabric like Knotty did here with his Stretch-Side Hammock
. 4) I make my hammocks 11' long and the channel seems (again, IMO) more comfortable.
All in all, it's personal preference. I've made both and for me, I only use the channel method. I hope that helps and please post pics of which ever method you make.