Buy the best you can afford that makes sense for that bike. In this case I'd say the Deore is worth it, and use the LBS to do the work. With bike parts in general you get what you pay for to a point, of course then at a certain level it becomes a price to weight ratio arms race that never ends. At this level the quality of the materials as you go up levels makes a difference. I would argue that if you'd had Deore on there to start with this may never have happened. it's Just a theory.