I've got split fins and non-split (solid?) anyway, I find the split fins are easier on the legs, but as was implied earlier in the thread, they don't have the same power. I guess it depends on the diving you are doing and personal preference. See if you can borrow some and try them out.
I've seen some pretty fancy looking fins lately that look like they have little pistons in the blades. Can't remember the manufacturer, anyone used them, any reports? Just curious to know if they are an improvement in technology or just marketing.