Cheers, Got the 20 £140 inc. next day delivery. Been playing with it and managed to load a full UK OSM map onto it, looks good so far. Need to work out how to record my rides and make track on the laptop to load onto the unit.
Possibly the wisest choice I have read about all day, you can also pair that little beast up to cadence and heart rate monitors, think you can even get a temp sensor.
I have one and fecking love it, my only tip is to shorten the lanyard you get in the box so that you can lash it to the stem / bars as the garmin mounts can be unreliable if it gets bumpy. Mine has only come off once in a couple of months, but 'twas at thirty going down a main road, so was glad it was tied on and not under a passing car.
Also that silicon case garmin make for it is a worthwhile investment, especially if you are a ham fisted twelk, like myself, that loves to drop anything new.