I have both piston and DI 300 blackouts, 9" barrel on the piston and 8" barrel on the DI. The DI uses a captured system from
Unrivaled. I use their captured buffer on several gas guns and they make both a standard and lightweight buffer for use with lightweight BCG's. Really good stuff that actually works.
With the DI guns I've built, a lightweight BCG has been the ticket along with an adjustable gas block (Riflespeed for the win) in terms of reliable cycling. I generally have a four click spread on the Riflespeed gas block between supers and subs. I've never really had a problem cycling any subs, let alone supers, with my hand loads using several powders. CFE Black is dirty as it produces a ton of gas and it'll force anything to cycle so it's dead reliable. I do use Vihtavouri N110 which as others have said, is clean-burning and is good to go while being faster burning than the VV120 and doesn't need as high of pressure for optimal burn rate. I don't find either of those to be "noisy" powders like say Lil' Gun or H110 (for subs) and both work for supers although the VV is better for supers than 300 Black and I'll take H110 over both.
My piston gun is all proprietary so there's no swapping anything out really. Still, it'll cycle factory Hornady 190 grain subs even in forced reset trigger mode at full auto rates of fire on the lower gas setting with any suppressor I currently have from full flow through to standard baffle cans.
In terms of cans and function, I have no problem with function on any of them on either rifle and I have everything from the Flow762Ti, to the HDQD762Ti, to a Diligent Defense Enticer S. In the middle I have a few Radical Defense cans which aren't ultra low back pressure like the Hux but not as restrictive as the Diligent Defense Enticer S (insert any standard baffle can here). I have the short and long versions of the RD cans.
In terms of perceived noise, I can't tell much difference between the Hux and the Enticer S. The Radical Defense CS3 is allegedly made for 300 blackout and I've shot it, no ears. Isn't horrible but I wouldn't do a mag dump or range day without ears. I've also been next to someone shooting subsonics with the Hux 762 Flow Ti and I was actually impressed at how good it sounded. But I was also on his left side, non ejection port side. My CS3 is the more robust
Haynes 282 super alloy version so it's the permanent fixture on my go-to piston 300 Blackout as it'll take anything I throw at it whether it be supers or subs. I have no doubt the LS3 is likely quieter since it's about 2" longer but I can't tell with ear pro.
Bottom line, the port pop is going to be the limiting factor at the shooter's ear. Piston guns probably have less port pop but mechanically seem louder to me. Downrange, a standard baffle can is going to be better but forget about shooting quickly. I've done that with my piston gun and the Enticer S in semi-auto and after about 20 rounds, I couldn't breathe. Indoor range so I'm sure that didn't help. I'd stay away from anything Dead Air just do to all the problems they've had, continuously, over the years. The Diligent Defense Enticer L in Ti is every bit as quiet as the Dead Air cans and cheaper to boot.
I have the relatively new Hux Flow 9K Ti in jail and I'm interested to see how it'll do mostly as it's full auto rated with 300 blackout and ultra light, under 5oz. direct thread. I'll mainly be using it on a ported 9mm PCC SD with radial-delayed BCG system which, if you want Hollywood quiet (and not suppressed 22LR) is the way to go.
