"If you do plan to use them, Option 1 may not be your best choice. IME, AVRs and Pre-Pros will likely get you substantially better subwoofer integration than you'll achieve with a traditional stereo preamp. "Likely" is the key word there, as absolutes are risky, but the bass management systems in pre-pros and AVRs really do this job well."
The OP's preference is pretty strong for 2 channel. Going with theater gear just to integrate a sub probably wouldn't be worth it for the hit you will most certainly take in overall SQ. It may be a little more work, but you can get a sub working well without all the processing. For a system like this, a sub made for music would probably be a better choice. Or maybe just use the sub for theater only.
The OP's preference is pretty strong for 2 channel. Going with theater gear just to integrate a sub probably wouldn't be worth it for the hit you will most certainly take in overall SQ. It may be a little more work, but you can get a sub working well without all the processing. For a system like this, a sub made for music would probably be a better choice. Or maybe just use the sub for theater only.