Just a few comments to kick off the discussion :
1. Other than the subwoofer, your speaker choices aren't really going to have much effect on disturbing your neighbor other than giving you the ABILITY to play louder (and more disturbingly) if you choose
2. Regarding subwoofers, the issue is that a sub which can play deeper (ie lower frequencies) will play those lower frequencies more loudly than a lesser sub will, even when you are playing both systems at the same apparent volume. You can turn the level of the sub down a bit relative to the other speakers, which IMO is more satisfying overall than a lesser sub turned up to the right loudness. With a better sub, you can turn the level back up and get the best of both worlds when your neighbor is out or during the early evening when you don't have to worry so much about noise.
3. Despite what you might think from playing with the HT wizard, the only real difference between QS4 and QS8 is reportedly the QS8's ability to play more loudly. Having said that, I went with QS8s anyways "just in case" they were matched better to the M2s (in my case) by virtue of having the same drivers.
4. Ditto for VP100 vs. VP150 -- if you have a larger room where you will need more sound coming out, the VP150 is felt to be much superior to the VP100. In a smaller room, they are apparently almost impossible to tell apart. I went with VP100 and have been real happy with it.
Based on my prejudices, I guess I would go with QS8s, VP100 and EP350, although by every account the QS4s and the EP175 should both be just fine for your room.
If you were going to be mounting the QSs on the side walls (or back walls a good distance from the listening position) I would spring for the QS8s.
I should make it clear that I have never had a chance to listen seriously to either EP175 or EP350 but based on specs the EP350 upgrade seems like a bargain.
Your room is going to be fairly "live" (ie reflective) so leave some money for "room treatments" -- depending on your domestic arrangements this might be spiffy-looking foam panels or partner-friendly wall hangings & rugs.
