I did some quick test:
n800, diablo, ld3w, frwd b600
usually in less than 30 secs, the bluetooth connection with the b600 is lost, while no problem seems to be present with nokia gps
I checked my previous gpx, and found only one of them where the heart monitor had been recorded for more time - around 1'40" - before loosing connection. If there is some debug trigger - or if you like to send me a binary with debug enabled - i'll be glad to be of any help!