Back in the "olden days" tandem and some hybrid manufacturers used to spec rapid fire shifters with road cranks and front derailleurs. It worked. My wife has a hybrid hanging in our basement right now that was spec'd that way from Specialized. Her bike happens to be a triple. If it had only 2 chainrings I assume the derailleur limit screws would simply block off one of the shift positions.
Fast forward to today. My philosophy is that, if I already own parts, I'll see if I can make them work. If however, I'm buying new parts, I'll buy whatever the manufacturer says will match. You make a big deal about costing 50% more, but how much is that in dollars? Are you going to be second guessing yourself if the initial set up doesn't go smoothly?