The edge 800 (and the 810) is utterly crap as a satnav.
I mean really shit.
1) it really likes ring roads, especialy Reading, which for a bike device is a nightmare
2) if you miss a turn it trys to get you back on the route rather than just re-calculating*, this is infuriating if you try and ride round some roadworks.
3) the postcode thing makes it useless
4) the screen isn’t very bright, so it would be useless in either sunlight, dim light, or at night (it’s barely readable on a bike let alone in a car).
*garmin car sat-navs are pretty bad for this too though TBF, tom-tom seem to recognise that you may have just turned off the road deliberately.
I bought my 800 with a mix of my own cash and some halfords vouchers, if I’d paid £300 of my own cash I’d have been really pissed off with how generaly rubbish it is compared to any othr £300 electronic device, as it only ‘cost’ me £200 I’m just really annoyed with it.
If you want a cheep occasional car sat nav, just get a cheep android smartphone and use the google navigation app, it’s great as long as there’s phone reception (if there’s not, just don’t get lost as it relies on the google server to re-calculate rather than the phone).