Re width, larger, "mess with my ride" --
My Zen was predisposed to be ruined by only one pannier, all freaked out about the lack of symmetry from only one bag. You'd be pretty darn surprised by it not mattering at all. If that's what's freaking you out, move past it and get the bigger bag for those just-in-case times.
I don't know either bag so no other specific comment on them. But I do love my Ortlieb back-rollers.