... it was a disaster. They assigned a handicap of -100 (to my Dragonfly 920, my first tri) and it was a spinnaker class race. I had no crew so I took someone from work who sailed but had never been aboard my boat before. (We really need at least 3 people to race in a spinnaker class and manage efficiently, and the word "efficiently" assumes time to practice and drill setups and take-downs.) We got cut-off by a smaller monohull on a downwind run with spinnaker up the other boat cut in from of us so I had to crash gybe and head upwind to avoid running them over. Fortunately we didn't tear the spinnaker on the spreaders (what a mess) and didn't crunch any fiberglass, so all things considered you could call that a success.
The problem with a boat like mine is that we can be handicapped when the wind is light, and all boats are still in displacement mode, but when the apparent wind is above about 10-15 knots we can keep accelerating while displacement monos hit a wall. Above a certain apparent wind level you get the same effect with monos that can plane. The performance characteristics are so non-linear between dissimilar boats that the PHRF formulas don't really apply except in certain situations.
The only time I've ever really had satisfaction in thinking the race results are fair, was when I raced Sunfish as a kid, and Mercury class daysailors in Wednesday night racing at a club about 10+ years ago.