I have one of the original checkmates, it has had the battery changed twice in it due to years of use, I typically get 2-3years of life from the batteries. I also have updated it to the latest firmware (for free) and the "click" buttons.
If you are new to Enduro format, the checkmate has it hands down with its late early bar on the lower display.
That being said the AMA National Enduro series has completely done away with "real timekeeping" so it may not be worth the investment. I have done enough Enduro timekeeping that a simple odo/roll chart/watch works for me 98% of the time. The only conditions that will get me is when a club puts together a race where the checks are in sections that I can make riding at 95% or better pace at something other than 18, 24 or 20 mph average.