Advice on buying a cycle GPS

Ok, this is neither - and it depends on how much you want to spend - but you don't *have* to buy a cycling gps unless youre after stuff like power and some more cyclocomputer-like/training aspects. The alternatives are  Etrex/Oregon/Montana etc which are handy in that they take AAs - hence some are popular with the long distance/audax crowd - and some versions of those will log cadence/HR with the appropriate Ant+ sensors. Being non-Edge they log  .gpx files, rather than .fit files.

Best to check, but it looks like both the Mio and Edge Touring come preloaded with cycling versions of OpenStreetMaps. OSM is an (open!)  user-contributed database and effectively free, there's a few  websites that have their own take of OSM too https://wiki.openstreetmap.org/wiki/Main_Page

http://garmin.openstreetmap.nl/

http://www.opencyclemap.org/

http://www.openfietsmap.nl/

and paid-for versions too:

eg https://www.velomap.org/

http://talkytoaster.co.uk/maps/ (well, uk are free, non-UK aren't..dunno what the advantage is over the free versions elsewhere but there's an FAQ)

On the Garmin (and other mapping Garmins) you can normally load up other versions of OSM onto the device or seprate SDcard (alternative is to buy City Navigator maps from Garmin, note that they'll be tied to an sdcard or to the Garmin device itself depending on which you buy. There's also OS maps, but they're non-routing and cluttered for cycling use, and ££)  I've used my Etrex on (walking/city) holidays in Europe as well as the UK, OSM often has the advantage that off-road paths are shown where City Navigator stops - but because it's used-contributed, can vary between pretty good and patchy.

Although the Mio uses a version of OSM, no idea if it'll accept OSM data (Garmin format or otherwise), tho' Mio may produce their own updates  - kinda necessary since OSM data continually gets updated (tho' I've not refreshed the UK maps on mine for a few years)

Some people have had the odd routing issue with OSM, but the only time mine's actually crashed was doing a postcode search on the City Navigator maps ! (OSM doesn't have postcodes). Oh, and generally on garmins you can have several maps loaded up but just enable the one you want to use. Best check internal memory capacity and/or the possibility of using an sdcard, not sure all garmins have a card slot.

If you go the Garmin non-Edge route, have a look at:

http://www.aukadia.net/gps/

If you want contours on OSM there's some info here

http://www.aukadia.net/gps/lwg_14.htm

tho' I think the (free) UK maps from talkytoaster have contours built in

HTH

I have the Edge Touring Plus (I wanted to record heart rate too).  Liked the fact it came with maps pre-loaded, and that they are kept up to date when syncing the device (but the updates take ages to download for some reason).  If I ask it to calculate a route it sometimes sends me down unsuitable tracks, but if I plot a route on the pc and upload it to the device it will navigate me round the course faultlessly with turn by turn directions.  Battery life is good for a day long ride, but despite the name you'd need some means of recharging it for actual touring.  It's also survived several drenchings without issue.

Switch off 'Recalculate' though, otherwise if it loses sight of it's satellites for a moment eg under tree cover, it will suddely start sending you back home...