XRAM - I am sure if the fitment were bad you would have heard negative feedback already. Since these don't actually mount to the car itself but rather to a frame that attaches to the car it won't require as much adjustment as a lets say a non-factory bumper, etc.
Shop should not charge you more than the required 1 hour. It might take them a little bit more than that if they have never mounted one before. They should tape it and measure it before applying the screws to make it official
I wouldn't hesitate to do it.