Graham,
Saw your post on sellling the suspension. Sorry it didn't work out. Anyway, I don't know if you remember but I work for REI and sell most of the Garmin line and few of the Megellans. I all comes down to what you are going to use it for and where you will be using it most of the time. Secondly, what features are most important to you and thirdly will be price range. Somethings to consider will be ease of use, size of screen, memory size if you are going to download software, antenna type and Waas feature which I recommend. The exporist is a good basic Topo "out of the box" unit for mostly back packing applications. The etrex line is very reliable and great starter units too but if you can afford it, look into the Garmin 60c and the 60cs. They have one of the largest, most versitile color displays plus all the buttons on the front as opposed to the sides like most other models including the etrexs.
The bottom line is the Megellan and Garmin are very simular overall.
Other options to consider are compass, barameter, altimeter, # way pts., routes, etc. if seriously don't need any or all of these features, why pay for them. If you don't already know how to use a GPS unit to its potential, consider taking a hand on course thru your local REI. You have to pay for the course but well worth it. Most of the returns we get on GPS units are due to lazy people not reading the manual and not able to figure out how to use them. They call it defective. Anyway, I hope that helps. Everyone's comments above me are all correct and which unit is better is personal choice.
Good luck,
Eddie
REI Encinitas, CA
PS I really like the 60CS.