we should have a pretty in-depth article on this (most pedals, and switching to a different setup) in issue 6, but that's a ways away. but as someone who's switched between the two, it's not quite as easy to find a beater coming from spds - but like with anything, practice helps. disengagement is easy, smooth, without the positive click though, and perhaps a more of a release angle (you can adjust this by swapping the cleats from right to left).
of course, the disengagement is more consistent as it gets sloppy compared to spds - they're not as affected by mud and organic matter. the lack the adjustments of spds though, in terms of tension. it it often sloppy where you are? if so, and if you don't bring a pit bike and crew, it could be a good choice.
Get egg beaters. Don't know what the condition are like in your part of the country, but in mud, sand, snow, ice or all three, you'll not be able to clip in SPD's. Egg's will always work. I think they are just as difficult to clip into, especially if you're trying to get used to them. I've had 8 years of SPD muscle memory to overcome when I got the eggs. They are different as far as how you have to hit the cleat on the pedal but you'll get it.
what i gotta do to convince you people, don't clip in..ride free and react fast... the whole issue of extra push/pulll from clipping in is actually a muscle memory thing too, fixed gear training should have taught you this...i have literature somewhere that actually backs this up, it's not just grant from rivendell, although he's no slouch , he don't race...
Eggbeaters. Switched from SPD's a few years ago and now use only eggbeaters - road, singlespeed cx, and mountain. I find that eggbeaters have a smoother, more consistent release and of course better engagement when mucked up. Aslo lighter (per $) and great clearance. Cooler looking to boot! Just need to use a decent shoe.