The Motor:
Go with the 790. If you decide to try to make more power, the 790 get bigger gains from the same upgrades. I've had two 790's walk away from me, and our bikes had the same upgrades (I have the 865).
The Ride:
I have no problems with mine for a tank full of petrol (about 130 miles). Common upgrades are springs and shocks and some folks ride after market seats. Lots of us ride stock. Kinda a personal thing. If it doesn't work out for you, the upgrades are easy and relatively cheap enough.
Trouble:
Not really much of anything. Rotors seem to warp on the 05-06 Speedmasters, and there has been a rash of CDI ignitions going out lately, but the dealers and the factory are taking care of most of them. The bikes are pretty solid.
You'll see around here we spend most of our time in debating the finer points of HP, how to make it, and what type of beer to drink whilst doing so- more than complaining about reliability.
Welcome to the clubhouse, friend.
