Ive found that increasing prices is the most sensitive issues with owners. IF your food is good,your portions fair, price increase are 99% never a problem. I think this is because those owners who worry about increasing prices are USUALLY the same guys who vastly under price their menu items. Prices are important, but you USUALLY only lose those customers who are bargain hunters.....and IF you run a top notch place, MOST of your customers APPRECIATE your WHOLE establishment and don't shop by price.
Sure, some do, and they leave and they will NEVER be an important part of your patronage. NOT every customer is EQUAL in importance. All you have to do to appreciate this is run one of those coupon deals. You'll see coupon couples ONCE.....and then never again, UNTIL your dumb enough to run them again.