hey there - i have been using speedplay for cyclocross (and road and mtb) for many years. i switched to them for the float thing - AND i hated the idea of not being able to clip out before a barrier in a cross race. i have used shimano, ritchey, time and crank brothers and for me i can easily say i love the speedplays the best. they do take a little getting used to but once that short adjustment period is over, you will love them too i bet. And regarding mud, i put a little silicone spray on them before the race or training and they are fine. But basically, when the mud is bad almost all pedals will have problems. I personally will never switch from speedplays (frog and X models). Oh, and another incident that made the switch to speedplays permanent for me is that i badly tore my quad muscle trying to dismount during a training when the non-speedplay equipped shoe didnt release just before a barrier. Another brand also gave me knee problems in both knees after only a short trial period but it took months to reverse the damage it did.
Hope this helps.