Got my fins, now a wetsuit!
Thanks to all who offered their advice. I ended up buying the Cressi Gara 2000HF (the black, stiffer model), and I love them.
Before my purchase, I was leaning towards the softer fins, because I was concerned that the stiffer version would be too stiff. After much research I decided for Beuchat Mundial Competition fins (gray, softer than the black Elite) and ordered them through a local dive shop. When they arrived, I found out that both blades were deformed. Basically, the blades were spherically curved, i.e., not just in one direction, like if you curl a sheet of paper, but in two perpendicular directions. Consequently, if you bent the blade in your hand up and down, as if swimming, the blades made an audible popping sound. I tried it in the water (not actually swimming) and the popping could be felt. I called Beuchat and they explained to me that all their fins like that. My experience was consistent with the review in Hawaii Skin Diver (
http://hawaiiskindiver.com/issues/300/finreview.html). I was very disappointed, because I otherwise liked the fin a lot -- good fit, comfortable pocket and light weight.
I returned the fins and went for the Cressis, available in a local shop. Although they only had the stiff black version (Gara 2000HF), I got them. The blades were perfectly flat -- thus no popping sound.
With trepidation I took them to the pool and discovered that my worries about stiffness were unsubstantiated. I could kick them with no problem, and liked the speed!
The real test came on my trip to Kauai, Hawaii, where I spend three days diving at the "Tunnels" beach. Without much previous training I easily did 45+ feet, and the fins performed flawlessly. Like the Beuchats, the Garas are very comfortable for my feet (I use them with 3 mm neoprene socks) and very lightweight.
I am hooked now! The next thing to get is a wet suit, so I will be seeking more advice on another thread. Thank you all for being such helpful community!