I have a givi e460 mounted to my luggage rack. I've only used it on one trip but I like it very much. Before that I used a soft tailbag strapped to the pillion seat a bit like the nelson rigg but not as spiffy.
here's the givi
and here's the tail bag
I like the givi because it's waterproof and easy on/off. It was like $150 at twisted throttle.
