IMHO I think double ear pro, plugs & muffs, is near mandatory around any of these guns unsuppressed if one cares about their hearing, braked or not they're LOUD. But, a can is nice and if someone likes using one, use one if you want. You can't control other shooters though, whether at a match or on just a random Sunday at your club, so unless you're by yourself, I'd double plug anyway if I was using a can.
That, and just the fact that I don't like having all that hanging off the end of a gun that's already as long as a mini-cannon, is why I don't run a can.
But yeah, brakes are fucking loud and the concussion and blast-wave sucks, fatiguing to be behind for too long sometimes.
IMO this is where things can improve: not all brakes are as obnoxious as others', so instead of trying to remove every last 1% of recoil they can, I wish companies would focus a bit more on the balancing act of maybe making them a little less obnoxious and loud, or at least try.
I have an Insite Arms Heathen 4-port on the way that I'm going to try on a 6mm, I decided to try it partly because it was one of the few options out there where at least their design acknowledges that keeping noise/blast off the shooter is part of the recipe, hopefully it works...