I fall into the mixed, I have a pair of bios and jets. I find the bios do a pretty good job fluttering when I'm milling around the reef. And while I can do a limited frog kick in them its faily sloppy and the glide distance is greatly reduced. My jets Are great wreck and cavern fins and the glide portion of the frog kick is easily double that of the splits. I also find the weight of the jets to be an added bonus when diving dry. Pretty much boils down to choice. Most of my buds that have splits pretty much always flutter, and the guys who have jets pretty much always frog kick. In my personal experience I preffer the splits for the flutter, and the jets for the frog, reverse ect. If you can frog in splits as good as someone in jets then more power to you. I havent been so fortunate in my findings.