An interesting thread.
Many years ago I used a Garmin Dakota which was really a hiking device but worked quite well with a bike mount.
It survived my high speed crash in Spain in 2011 and it was interesting to see that it continued to record the route when being taken to Guenica police station by the attending officer!! It has however made me reluctant to attach my phone to the bike especially with the weather issues but each to his own.
Since then I have used a Polar device and subsequently the Elemnt Roam.
I had a slight issue with the turn by turn navigation earlier in the year when trying to short cut my route back to Edinburgh. I thought that the countryside looked familiar and found I was on my way to the start of that day's route not an earlier route from Edinburgh. Don't ask.
Recently I updated to Version 2 to as it seemed that the screen would be clearer for my old eyes! Indeed it is but having set it up and starting a ride with 30% battery I was surprised that the battery ran out mid ride which had never happened with the original model. I wondered if the battery life was as good.
However Nearholmer seems to have inadvertently answered my question as the battery died not long after I switched on the turn by turn navigation which I don't normally use as my routes are fairly predictable. I didn't realise that the screen had such an impact on battery life, although I suppose it is obvious, and explains why the new brighter screened drained the battery when the old screen might not have done.
if one has a map on view on screen all the time, that places quite a demand on the battery, something which applies irrespective of the tech