FWIW: You can learn to spin just fine without foot retention. If anything, your technique will probably be better without it. In goldsprints I max out around 215 with clips and straps, more like 200 without them. Fastest goldsprint guy in DC (that I know of) rides platforms on his tricktarck and can outspin me any day.

It's interesting hearing Hairnet talk about how he focuses on the bottom on the pedal stroke to spin, because I focus almost exclusively on the top; kicking through with my quads before I start the downward stroke.

Riding fixed will also help a lot in terms of getting your legs used to that circular motion at high speeds. It's definitely a crutch if you rely on it too much, but like I said... in terms of just getting used to the motion, go down a big hill riding fixed. Do it every day. You'll get faster.