I just sold a Zumo to go to a Montana. The Zumo was a great unit. Easy to see while riding and had no issues. The blue tooth to my helmet was great. I used it on my Vstrom. The only reason I switched is that I wanted to upgrade my 76CSX to a larger screen to use on both of my KTM's for offroad use. You can't load tracks on the Zumo, only routes. A lot of my offroad riding uses tracks. So, if being able to use tracks is important to you, get the Montana. BTW, this was on a Zumo 550. I don't know if any of the newer Zumo's have the ability to use tracks.
2009 BMW K1200LT
KTM 525 EXC