I have a G-Shock GW-1400DU with solar charging and auto time updates. Like Ross mine has stayed on high for the two years I have had it. Out of the box it was on medium and then went to high on the first sunny day. I guess eventually the internal rechargeable battery will need changing, but they seem to last for 5+ years. It does go into sleep mode if it is kept in the dark(or not moved?), I can’t remember how it works but the hands both point upwards, and then realigns itself when moved – this caught me out on a 12 hour solo race in the dark, at about 2am I though it had broken as it was no longer displaying the time!
The automatic update is very good, and you forget it does it. Mine has a daylight saving setting, so when the clock shifts it does that too. The only downside is if I go out of the regions covered by the time signal I have to dig out the manual to adjust the time as I never need to adjust it normally.
I don’t think I would bother buying a ‘normal’ watch again.