Its just my personal preference.
Everyone seems to use their GPS in a slightly different way. The way I use mine plays to the strengths of the old Etrexes. Or you could put it the other way, I've been 'trained' by continued use of the Etrex over many years, to navigate in a certain way. And, faced with the newer models, find myself in an 'old dog new tricks' situation. Hence my preference (and yes, I too have just bought another Vista at the £90 price).
If you have a clean sheet and this is your first GPS, then IMO there would be some advantages to getting a newer model, and not saddling yourself with the idiosyncrasies of the older types. All Garmin's current map-based leisure GPSs have a UI in common, and are 95% the same apart from the packaging -
except the Legend and Vista. These devices seem to me to have a half-life of about 4 years, so whereas in the past you could buy a Vista knowing that there's a big user base out there, looking to the future that user base will consist mainly of people with the newer models all very similar).
Oh, and BTW - stem-mounting is over-rated. These screens are quite dim in daylight and getting the viewing angle right is a big help. Stem-mounting prevent you from doing this. (Plus in my case, the thing would soon be swamped in salty sweat.
) Anyway, the mount for the E30 can do stem or bars (and is a very secure system, better than the old one).