Thanks all, will order proper - buy once, buy right eh?!
Yes. Good call.
You can see upthread that i bought one about three years ago.
I now have three genuine Garmin mounts on three bikes.
All have been firm as a rock.
Now and again the zip-tying lets the thing turn a bit on the bars so that the Garmin needs to be turned a bit.
Buit this can be corrected every now and again (every few months maybe) with a bit of old tube to give the holder a grip and by tightening the zip ties.
But this doesn't mean the unit will come off the bike.
I have total confidence in mine.
Yes the mount is expensive for what it is but look on the bright side.
You save by:
Being able to use standard rechargeable batteries
The Etrex 20 is substantially cheaper than some other (including Garmin) units some folk seem to feel the need to buy
You can use free and excellent OSM maps - I recommend openfietsmap,.