The splits everybody here seems to be mentioning are among the softest bladed splits out there. Soft blade equals easy effort with more difficulty using alternative kick styles. My atomics splits have about the largest blade among all splits, and are among the stiffest. I have no problem whatsoever doing helicopter turns, frog kicks, etc. With the softer smaller blades on the Tusas, Apollos, and to some extent the soft version of the Scubapros, there is obviously going to be a difference in how well certain kicks will work.
As a real life example, My wife has older paddle fins, and I used to have even older Tusa paddle fins (1988 vintage). On all of our previous dive trips, she would regularly come out with 400-700 PSI more than I did. Since I bought my split fins, not only do I no longer get ship splints or sore ankles, but she no longer comes up with significantly more air than I do. During our last trip to the Caymans, the most she beat me by was 200psi, and I actually beat her by several hundred PSI on a couple of dives. As an added bonus, if she has the camera and we see a ray or turtle ahead of us, I can swim fast enough usually to go out and around it before it spooks away from her. That way it is more inclined to stick around and let her get some photos. I do have to be careful not to outrun her sometimes, because it takes so little effort to go fast, I sometimes outrun her without even realizing it.
As for the silt thing, that is all about buoyancy control. Buoyancy control isn't awarded like a patch with a certification, it is practiced and developed. If you have ever watched the PADI nitrox video, watch the girl diving during the video footage. She is always pointed upward at a 30 degree angle from her buddy. I would assume she works for PADI, and has had all kinds of access to training, but clearly she was negatively bouyant the entire dive and had to kick upward to stay even with her buddy. it is also possible to be neutrally bouyant with your legs lower than your head. That is alot more likely to be the cause of the silting than some mystery flaw in the split fins. By design, the splits direct more water straight behind you, where as paddle fins have been shown to direct water upward or downward in greater volumes, which accounts for their difference in efficiency versus splits. If you are in a quarry on a weekend, its a good bet that you have alot of newbies wearing splits who either let their dive shop direct them to them, or read all the scubalab reviews showing that splits were more efficient. You are also alot more likely to see experienced instructors and DMs wearing their "pool" fins or who haven't wanted to spend the money yet to upgrade to splits.
In the end, it all comes down to personal preference, but I think anybody who dismisses splitfins because they think they silt up water or because they heard you can't turn around in them is missing an opportunity to try them for themselves. Its one thing to put them on in a pool for 20 mins and decide you don't like them, its another to wear them for several dives and get used to them, and still say you don't like them.
AggieDiver