I just pulled the trigger on a Foretrex 301. Primary reason is that when flying I want to read altitude not cabin (pressurized) altitude.

With the 401, the baro altimeter is constantly updated by the GPS, but in a situation where baro altitude is 5000 ft and real altitude is 15,000 ft, it gets a bit out of calibration. The 301 measures GPS altitude which for my purpose is just fine.