This Mudman (Casio term for mud resistant, possibly more rugged than standard G-shocks) is very similar to the G9000A. There is the added feature of a rally timer for those who need it. This is the same watch as the GWM850... minus the mudman name and a few dollars cheaper.
  I didn't need the rally timer. I did, however, want to be able to read the day, date and time of day on 1 screen without having to toggle between the date and day as on the gw9000. Of course, there is a trade off... too bad we can't contact Casio and let them know that tiny differences DO make a difference... when in timer mode on this watch, you can't tell what time it is.  On the GW9000A (and GW810D), you are shown the time of day on the same screen as the countdown timer. On this watch, you aren't given the time of day in timer... instead the window that could/should have the time of day tells you how many minutes your timer was set for.
  Great feature set on this watch and so far, not a scratch (and I am really rough on watches). Also, I love the auto illumination feature that I didn't think I'd care about when I bought the watch. It's really cool not to use 2 hands to turn on the light... and on this watch, you can set it between 1.5 or 3 seconds duration.

Don't love the red, but that's easy to fix by removing the paint from the lettering and painting over the metal ring under the bezel.