Agreed 100%. The difference in sound reduction between the 6.5 and .30 cans are minimal - I can't recall the number, but it was insignificant. Not that you would even notice, but having the flexibility is invaluable. You won't regret it; I haven't.
I have a Sig can and would recommend it overall as it performs very well and has had zero issues, but if going with a QD model you should be aware of 2 things:
1. Sig does a really good job of not mentioning this...the QD mounts are meant for the MPX-style barrels that have a taper cut into it past the threads. If your barrel(s) have a traditional square should, the darn thing will only thread on a turn or so. Sig seems to think this is not an issue, but I didn't agree. I had my barrels turned to have the taper on all but 1. Probably not a huge deal but kinda ticked me off considering the nature of buying cans.
2. Sig is notorious for announcing all kinds of new equipment, then only actually bringing half of them to market...the other half is always backordered. Never have seen their can wrench in stock and have been waiting for the mythical flashbrake and 2-chamber micro brake for 4 years now...
Had I known all this up front, I would've spent the extra 2-300 and gone with a TBAC, which is quite a bit lighter and has a spotless reputation.