Choosing a hand held GPS

Hi All,
I own an older Magellan Sportrak (base version w/ no map). I am
generally happy with the unit and would like to upgrade it to a better
one. My idea of better is listed below.
1) Less power hungry. Sportrak lasts only about six hours on two
AA cells.
2) Support for map and navigation. I don't need voice prompts.
But, I need the ability to change the maps.
3) Basic information. Compass, Lat/Long, trip, bearing, speed etc.
This is a must have feature.
4) NMEA support. Sportrak has basic support. A unit with better
support would be useful.
5) Availability of tools for Linux to save and restore routes and
way points. Need not be by manufacturer.
6) Availability of fixtures to mount in car dash board. Not every
time. This would be used more hand held than in a car.
Any ideas? So far, I found Garmin eTrex Vista and Magellan
eXplorist 600 to be close to what I need. The Magellan Triton series
seems to be suffering from feature creep. The hand held units from
Trimble seems to be too much for me.
Thanks in advance.
Pradeep