No real experience of the 200 to be honest, but I've used a couple of it's big brothers - the 705, and latterly the 800 - by and large they're great, and I'd be very unwilling to return to a non-gps cycle computer after using one of them. The only real competition to the Garmin is the Bryton GPS units and smartphone apps. Again, I've not used the Bryton units but from what I can gather you appear to be a little tied to the Bryton Bridge software, whereas pretty much all the internet seems happy with directly pulling .FIT or .TCX files from the Garmin head units. As you mention riding under tree-cover, I can happily confirm that the GPS receiver in my 705 (2 generation old tech. from garmin now!) is WAY, WAY better than the GPS app. in my Android phone, and the battery life is in a different league altogether.

Personally, I'd be sorely tempted to take the next step, and go for a Edge 500/510 - which has capablilties to link to a HR monitor, cadence/speed sensor (speed being particularly useful for static/indoor training) and, in extremis, even linking to a power meter!