I've always liked the Nuvi. I've used them for years (in my car), and currently have a 765T that has, and still does, work flawlessly (although, I voided the warranty by replacing the "non-replaceable" battery). That being said, I tried it on the bike, and found it requires it's own farkling to get it to step up to what you really need on a bike (including downloadable route planning, brighter display, waterproof, etc.
So, enter the Zumo. I have a 350LM. Not perfect (in fact, I like the Nuvi's interface better). However, it does do everything you really do need on a bike. It's brighter (however, there are still times glare prevails), it's waterproof, handles downloadable routes/waypoints/tracks/etc., and it's (supposedly) built tougher for the higher vibration environment on a bike. I haven't learned everything the Zumo does... it's extensive.
With the introduction, recently, of the 390LM, the 350 has dropped in price significantly. It *is* a Garmin, and as noted earlier, their service is great (I *did* have to return an original frozen 350, for a new one, and they took care of it directly with no questions asked, even though I didn't buy it direct).
So... for a GPS on a bike... my feeling is pay now, or pay later...
2017 Pearl White 650[/B]
AdventureTech lowering links and GPS mount
AdventureTech +2" SS braided brake line
GPI spools, SW Motech risers
Givi XS307 Tanklock bag and Givi 46L top case
Suzuki hard case saddlebags