Float is ok - you can set the release angle to 15 or 20 degree (from memory) and they float up to that point.
I bought these when I did the Fred Whitton challenge in the Lakes and was unsure if I'd have to walk or not so wanted to use my mtb shoes. I had Spec shoes too and had to just cut away a small amount of grip around the axle to take account of the bulge of the bearing housing on the pedal - nothing major.
I now use them on the fixed commute bike where the double entry is handy, on my winter training bike when I prefere my warmer mtb shoes to handle the grime, and when I turn my cyclocross bike into a tourer and want to be able to walk around like you. They might not be quite up there with my dura ace pedals on my race bike but they are very good.