I'm that Californian Jim from Boston mentioned... We use Garmin's (I have 810 and my husband a Touring) and think they are amazing! Not perfect, but... I'd always thought the technology would be intrusive on our peaceful tours, but in planning our LEJOG (Lands End, Cornwall to John O'Groats, Scotland; 1100 miles) last year, the advice from those with experience was to get a Garmin or you will probably get lost. Britain doesn't seem to bother to mark many (most??) country intersections. The Garmins saved us countless time which would have been spent huddled over maps at intersections! We've done 4 or 5 tours in France, and all were pre-Garmin for us, and we did just fine with map and compass, though.
Never even considered going without them on our Sept 2015 tour to Massachusetts! And for a possible tour in France in 2016 I wouldn't dream of leaving them home. We always have paper maps just in case -and for getting a larger overview.