I was asking the very same question about 9 months ago, and even though I should be close to getting the new can, I'd be lying if I said I haven't revisited the dilemma!
I had really similar priorities and weighed a slew of similar advice. All signs pointed to the Ultra 7 & loudly. Then I went and shot all of them: Ultra 5, 7 & 9, Nomad, Sandman Ti, Half Nelson & Full Nelson. I wanted to love the Ultra 5, but it was loud. Too loud to shoot more than a couple of times without ears, but I could see it being an awesome second can for sure. The 9 and Full Nelson were both amazing (9 was better), but both were too long to pack around for my taste. The nomad was shockingly good too but if I just wasn't feeling the mounts. Between the 7 and the Half-Nelson, I made the wildly unpopular choice to buy the Q. To my ear, the HN was a bit quieter, but it also shot nice groups with less shift. To be clear there was no apparent difference between the two in terms of precision. Recoil impulse was also similar between the two. I wanted to like the 7 better, and if I had it to do over again, I would probably just by the TB, but I did what I did.
Someone else mentioned the mirage on ti cans, and I imagine it'll be worse on the q, and the addition of a sock will make it pretty girthy.
Good luck & hope your wait isnt too long!