Hipo engine builders and the likes usually go floating. They are easier to take apart (well, except for them darn spiral locks) without special equipment. But a lot of street strip engines use pressed fit.
So, a lot depends on what pistons and rods you buy.
ya really no big benefit either way in my opinion. Full floating give you the flexibility to mount the pistons on the rods at home, but that may be offset by the pain-in-the-ass learning curve for installing the spirolocks (two per side, four per piston)
They may be available but, why? Teflon is to soft to be a good pin retainer. Better is "Nylatron" plastic. Buttons are ONLY used in drag race engines that are disassembled regularly. Using them in any other application WILL result in extreme wear to the bores in line with the buttons.