Mike I have raced against 7.9's since they first came out. That was when I was racing my Niagara. They are very stable and no one seems to worry about anything they might come up against on the lakes.
The dagger board is 600 lbs, in fact the largest winch on the boat is used to haul it up. They have a wide flat bottom for good initial stablity and also internal ballast but I forget how much.
We have about 8 in Sarnia and I have not heard any complaints. Your best bet is find one racing locally and go crew with them. I considered one this winter but went with the 9.1 instead. I really wanted some interior but now I cannot afford sails.
Also I like a boat with lots of feel in the tiller, the 7.9 has little feedback here so you really have to watch the ticklers.
PM me if you want to come to down and race on one.