Contrary to other situations where "size matters", the size (& location) of a ski shop doesn't matter. Every type of shop, large and small, can screw up a job. You can't generalize this way.
A few yrs ago, I decided to trust my brand new Stockli Stormriders to the tender mercies of a small (but long established) storefront mom&pop shop for binding mounting. On first glance it looked he had done like a nice job, so I didn't detect any error until I skied on them. It turns out that the bindings were located about an inch forward of where they should have been. When I brought them back to the shop, the owner/tech claimed, "I measured them". I then pointed out the mounting mark that the factory had so nicely provided for people like himself
Last year, I brought a new pair of Explosivs to a much larger local store (it is one of 2 stores in a local chain that covers only skiing & biking). I had a pair of demo bindings that I wanted mounted. "Sure, no problem, the main tech said." I even double checked by asking specifically if they had a jig that would fit the 95 mm width of the Explosivs. I was reasonably confident in them since I had occasionally used this place for tune-ups in the past.
When I got the skis back, the bindings themselves were both properly located at the correct fore-aft position on the ski, but one was located in the center of its rack, but strangely enough, the other was all the way to the front on its rack. They had obviously mounted one of the racks in the wrong fore-aft position. Of course, this meant they were unable to be adjusted and hence completely useless as demo bindings (ie, as loaners, for my kid, etc.) as I had described to them when I first walked in. Upon closer inspection, it became clear what had happened. There was an earlier set of mounting holes on one ski where the tech had first tried (unsuccessfully) to mount one of the bindings. Of course, that problem happened because he really didn't have the proper jig for powder skis. He realized he couldn't put a new set of holes right next to the original set, so he simply mounted one rack was in the wrong position.
When asked why this wasn't brought to my attention, he said that since I was an individual, he thought I would never need to readjust them - he had completely "forgotten" that I had told him that was exactly why I was putting demos on them.
After a minor debate with the defensive, insistent tech ("They work! ... No they don't!") I walked away from him in mid-sentence and found the general manager. He made sure Volkl comp'ed me a new pair (which I had mounted elsewhere).
In my personal experience, the best, most consistent ski work I get is from the two local stores that also get the best word-of-mouth and internet recommendations. I think that seeking recommendations from others about the best local store is about the best you can do. Beyond that, its a crap shoot.
Tom / PM
PS - I once actually did get a great on-the-spot tune from a shop at a base area, but I did this by going in when it was almost empty, befriending the 17 y.o. who had been hired a couple of weeks earlier, showing him how to adjust his machine for something other than 1/1, and standing right there while he fed my skis through it. [ June 22, 2003, 10:03 AM: Message edited by: PhysicsMan ]