I also installed a Utopia
Just finished installing my Utopia backrest (for the 650) this am. Started last night. Probably four hours total. It went ok. The directions are not that great, and i'm no mechanic. Have to be very careful with a few of the screws when taking the seat off, as when they fall, they fall into cracks and crevices that are tough to get at.
Haven't ridden with it yet, but I think it will be quite comfortable.
Hope to get my Clearview (XL) Shield on Monday.