One thing that I haven’t seen mentioned with regard to Flips is that they are quite “slippery” if you need to walk across rocks during launching (the plastic sole doesn’t seem to have anywhere near the traction that the rubber sole Vipers or Duck Feet have). Also the cloth straps wear from walking where they cross under the bottom of the plastic sole. Apart from that they were very convenient for loaning to friends with feet that were different size than mine, didn’t require much storage space, and are very light weight. Unfortunately a couple of years ago they seemed to develop “legs” of their own, and one of these days I expect to buy another pair (primarily for anybody with different size feet who wants to try one of my boards).
For day-in, day-out surfing I use DuckFeet (Orange/Blue-Extra Large, from how many years ago, I don’t know–possibly 30 or more) for kneeboarding and hydrofoiling, and Vipers (don’t know version #, but tip of blade is 8" wide and extends out 12 3/8" from foot opening on the bottom face, yellow dot, extra-large) for bodyboarding. (150#, thick calves–need 3-1/4" ‘dart’ added to calf area on O’Neal Psycho II to fit).
I grew up bodysurfing at the wedge where UDTs and Vipers reign. I’ve tried tons of different fins. The UDTs are awesome but you gotta’ have the legs for them. For me personally, I stick with Vipers (both for bodysurfing and riding a surf mat). I’ve been wearing the V-7s exclusively for 8+ years now.
One tip for making them more comfortable is to fashion a heel pad out of neoprene (like an old wetsuit) and wrap it around the heel strap of the fins. Staple the ends and glue up the seam with heavy duty neoprene glue (it will take a couple of coats to get a good, long-lasting seal). This will save your ankles and heels from blisters and calluses. It will also give the fins a bit of a snugger fit so they can’t get ripped off your feet as easily during duckdives, underwater somersaults, trips over the falls, etc.
I’ll post a photo later if I remember.
All of the Vipers now come with the footpad on the top of the footbed. You can customize these too by cutting them back or adding extra neoprene in key places as needed. Viper used to sell footpad kits which were basically a pre-cut piecie of neoprene and some superglue so you could make or add your own footpad. I don’t know if they still do this though.