Yes I'd buy it again. This is my first gps and I held off for over a year after it was released, partially to let the bugs get sorted out but also because I felt my iphone worked fine for mapping. I've really enjoyed the Montana and having a map in front of me is much better than digging the iphone out of my pocket all the time. It's really changed the way I ride.
On gpscity.com there are pics of a user with the larger RAM ball mounts, the 1.5". I went with this and it's rock solid. No movement and it doesn't take a lot of pressure to lock it down. I'd suggest you try this RAM mount first since it may be all you need. If you decide to grab a Montana you'll already have everything but the amps mount.