I have had the L1 Classic for a couple of years without a problem. When I first got it, I chose to do the same as you, in that I had a Z5500 sub. It worked, but it didn't sound as good as on my old setup. I ordered a Bose sub right away and the difference was astounding. The reason is that the Bose sub becomes a part of the entire system when connected(crossover). I would say try yours, but it won't be the fault of the Bose if it is not to your liking.

As far as I or II is conscerned, there are pro's and cons. The model I, or Classic, has four inputs on the base unit, and does not need a Tonematch. I have one anyway, for additional functionality. Some say the spread is wider on the model II, but not that much. Some say the sound is better, but the tech boys at the Bose forum dispute that.

I, obviously, think you are going in the right direction with a Bose, the particulars are up to you.

Good luck
Bernie