For the most part with servicing we are talking of a change of oil / filter and some tyre kicking, which is not hard for anyone to get right and if you did not want to do it yourself any back street car mechanic could do for half the price - just without the computer to plug it into and generate some other costs for "failed" parts you had never notice failed.
On the plus side most of the mechanics will have had some training and lots of experience and should be easily capable of doing most work very well, on the negative side the do it all day long and its "just a job" and not their pride and joy, they could be sloppy / not give a fuck but its still unlikely they would fuck up most stuff.
The biggest fear for me is has the work been done, bought a ZX9R once, had recently had a full service incluing tappets for about £500 (15 years ago so about £15k in todays money taking into account recent inflation) As I had an old work colleague who was a one-man-band motorcycle mechanic I took it to him for a check over - airbox full of crap, maybe never opened - so onto a valve check, he said 100% nobody had ever been in there before.
Overall we don't hear of many bikes going bang, or bits falling off as you leave the dealers (although a mate of mine had a service in the 80s on a new bike and it was dripping oil when he got home, we found the sump plug hanging on by about 2 threads, another mile or two and it could of got ugly!) so overall they will all keep your bike running.
What they tend to struggle with is time, pressure on the workers to do X amount of work per day, when I service my bikes myself I take off the brakes calipers and clean up the discs / pads / pistons, grease evrything up really well, and re-assemble with all but bodywork fasteners tightened up correctly with a torque wrench (having checked the manual to see if the fasteners should be greased or loctited) and I bet a lot of this atttention to detail can get skipped.
Anyway, premier have seemed fine with me for the last 7 years, and I always felt that if I had an issue I could take it up with the guys there, hopefully the new owners won't fuck with things too much!