If the mechanics are good, I wouldn't think it's that important. Can they do warranty work? That might be the only downfall should you need warranty work.
I use Rizzon's in Middlesex, bit of a drive for you, though. They are a Suzuki/Kawasaki dealer, but I've also had them service my Honda. They'll work on most brands.
I actually do most of the basic maintenance myself...oil change, brake pads, brake bleeding, tire changes. The only thing I don't bother with is engine work....valve adjustments, plugs. The plugs probably would be doable, but I figure if they're in there for the valves, just do that while things are apart. Just got my Versys, so not sure how hard it is to get to the plugs, but on my 4-cylinder bikes it was a pain in the butt, and not worth it to me to do!