I completely get the importance of leaving the adjustments up to the shops and technicians but honestly, these "certified technicians" don't always care (or sometimes don't even know) what they're doing and get sloppy. They're often just ski bums like you and me who just want to crank out as much work as possible so they can get out on the slopes for a few runs during their breaks.. The "certified" technician (from Christy's Sports at Keystone) that mounted my 4frnts put me at 5.5 and I almost killed myself on them. I've prereleased simply turning, even after telling the shop to mount them at "3+ because I don't want to prerelease". Once, I made a turn and prereleased as I was trying to align myself to drop a cliff. I've also prereleased in a tight chute twice, even after turning the DIN up from a full turn (5.5 to 6.5). Now, in my opinion, putting a binding at too low of a setting, even after being explicitly told how aggressive a skier you are is equally as dangerous as an amateur cranking their DIN up higher than it's supposed to be.
Take home story: Don't adjust your bindings by yourself unless you have researched what you're doing, know and acknowledge the risk that you're taking by doing so, and have had previous problems with releasing when you're not supposed to. Certified bike mechanics wont' tell you not to adjust your bike by yourself (they'll often teach you how if you ask), so why should you not be able to adjust your skis by yourself?
/My 2 cents on this subject...