Ben,
These are my first pair of longfins so I can't compare them to the others, but I love them. The blade is slightly thinner and longer than the previous ones, and also slightly stiffer than the HF ( from a mate who's had both).
They don't feel too stiff. I got used to them fairly quickly, and even though I don't dive often and am in poor shape, I swam with them for three hours last week and only experienced very minor cramping in my feet at the end of the dive.
As for surface characteristics, I can't complain either... it's just a matter of trying different styles and getting used to them. I think the only way longfins would be really great on the surface would be if they were either so short or soft so as to render them useless for depth.
They are light, the footpocket fits (me) well, and power me up and down really nicely. So far I've only taken them to 23m, but since I used 20 year old snorkel fins to 21m, the carbons would have to be a damn sight cheaper for me to make the switch.
