Oil type thread or not, here goes...
Believe it or not, I went cheap, and got a PeakLife form chinavision.com ($148.58 delivered). I then got some free maps and software from the Pirate Bay, and have figure it out pretty well, I think. It does have a software issue that will dump the software if you click on a turn when looking through all the upcoming turns, but seems to do well (for me, at least). Waterproof, easy to mess with, and you can select off road tracks, but I don't use those on my ST, so I can't say how well that works. I don't have any map updates (since I just got a software set from filesharing sites), but they are available (no idea on costs). I know, I know, not strictly the way I should go, and I'll probably buy a real software set eventually, but I just wanted to check and see if I was throwing money away, or if it was a good unit, and I think it's OK.
I have it mounted on my dash, using Ramball stuff, after modifying the mount that came with it. In direct sunlight, it's a bit tough to see, but it does have BlueTooth built in, so it can also talk to me (which I have yet to use). I now use it as my full time GPS on both the bike and truck. It's done VERY well in highly congested areas (like the multiple overlapping highways in Houston, New Orleans and San Antonio). One really nice feature (which may exist in every other GPS except my Nuvi 660, I don't know) is that it also shows which lanes I need to be in when coming to intersections.
I like the fact that I can create routes on Google, save them to a KML file, and dump it right onto the GPS using USB, then when the software loads, just load up the route. It will then take me to the beginning of my route, and follow it through. Nice that I don't need any special software to do this (like Garmin BaseCamp or MS Streets and Trips). The more waypoints I stick in, the more accurate the route I can create, using as few or many of those little backroads that we all love to ride.
I also have written a pretty extensive review, with lots of directions on doing these things with this GPS, but I don't remember if I posted it up here or not. If not, and someone wants it, I will cross post all the instructions here.