I have the same system, and I love it. They actually just started offering an upgrade to existing users that ups the data rate from 5Hz to 10Hz. If you have a bluetooth capable Windows Mobile device already, or can find a way to properly secure a laptop, then you only need the MQGPS unit. You will get alot more out of a system like this than you will just a transponder setup.
It will actually plot the course out, you can get segment times, etc.
Best part is since many different people have the same system, you can swap data and learn. This year’s ES class winner at the 2007 Solo nationals was kind enough to share his data with me (along with Mike and Dave) so I could see just how badly I sucked.