I have the X5 pedal and I'm going to upgrade to the X2 or 1 sometime before race season. I've replaced my cleats once since I got them 1.5 years ago. They weren't having a problem when I replaced them, but I wanted to be pro-active so that I would not have a problem during a race.

I used Time pedals for a little while because I wanted to try re-centering float, but I switched back to the speedplays after about two months.

Avoid mud/dirt/sand when you're walking around, but if they do get clogged, just stomp your feet (my riding buddies dubbed this my "speedplay dance").