I have a Foretrex 101 that I dearly love. It does have a few shortcomings (modest sensitivity, no USB interface) but more than makes up for them with its very small size and very light weight. It also uses AAA batteries (including Li batts)that I can multi-purpose with my headlamp. I typically don't use the wrist strap, but I just carry it in a hip belt pocket. I use the battery-save mode and only get it out and turn it on when I need to check my position on my paper map (UTM coords.) It actually has decent sensitivity (better than my Magellan Meridian color that weighs about a ton and is huge!)
This new Foretrex 301 sounds almost perfect to me. If I didn't already have a perfectly serviceable GPS I'd buy this one in a heartbeat. The 401 sounds a little gimmicky for me, but others may find the extra gizmos and functions useful. It seems to me that the Foretex 301 may be the "go-to" GPS for UL.