what did you do with your fazer today ?

[nick crisp]

"The bike will lean better round corners" - are you sure?
Ok, I see it for a one-off trip where you'll be using mostly motorways, but I definitely don't see it improving handling. Plus, you said about your panniers being wider than your bars, yet you're going for a 2 wheel design, "max width"?
Also think Mickvp may be right about where you mount it from, although I also wonder about the strain on the rear wheel spindle with Luke's example. Well, it's all been done before and I guess you'll have researched it thoroughly? I can't say I know a damn thing about it really.