I never trust the reading of any electronic device compass. You'll run into calibration problems... plus they are not accurate at all in comparison with a real compass. The compass on my Casio dual-sensor watch is barely usable (you learn by experience sometimes).

Those are "nice to haves" and fun backups, but I would never use them more than to have a general idea of where i'm going (north, south, east or west).

There is nothing like a real, quality compass to get accurate readings. So like another person said, I would not pay a large amount to get an electronic compass on a GPS. Since you already have a Silva Ranger, I wouldn't bother getting a GPS with electronic compass.

For the record, I use a Victorinox DS-50 compass (similar to Silva Ranger) and a Garmin eTrex Legend HCx GPS receiver.