I must say i am rather luke-warm about *ever* making 1.6 minimum. The few interesting things (functionally) that happened in 1.6 are well covered with reflection, and I'd be tempted to just wait until we can do 1.7 base ;)
As for being able to support multiple versions, I generally make different accounts (release15, release16 and release17) that I permanenty use for releases for the different targets, and I just su to the appropriate account. The debs for different versions are safely tucked away ;) Kristian