I would opt for a 100 if I was doing competition.
Flying the one I had - Brian Copfer won the SW IMAC Championship.
The 80 on a tuned setup is a good Sportsman machine but I like more power for Unlimited class stuff.
The 80 is a favorite of mine - I haved used it in a number of models and for my own tastes, I like to have it in a plane under 200 squares and under 25 lbs
Remember tho - We do most of our flying at 4500 ft elevation.