What swifferman said is definitely true, though you had a bad experience you SHOULD do more braking with the front. The only reasons I have for supporting getting the rear disc brake would be that:
1) Your past experience and obvious dislike to the idea.
2) If you bend the rim a little with disc brakes, performance will not suffer.
3) Since you mainly use the rear brake, you will want consistent braking rather than the in-consistencies that could be from rim brakes(dents, wobble, water)
Your best bet overall would be to try to get both, but the decision is yours.