I'm tempted to say that, like there's no such thing as bad weather, just inappropriate clothing, there's no such thing as too loud - just inappropriate gear.
If your amp can't be heard, get a bigger amp and/or cab. If you can't hear your vocals, get monitors or IEM's. If your ears are ringing, get custom earplugs. You can't say 350 watts [i]should[/i] be OK. Either it is or it isn't. If it isn't you need more.
Of course you could always fire the loud ones or leave. I been in many bands trying to rein in bloody guitarists by not joining in the volume wars. It usually had no effect other than I was told that the audience couldn't hear the bass. I was always playing in good bands with good players and didn't want to leave so I joined up and went as loud.
The bottom line is, if the gig tells you you're too loud, you're too loud. If they don't then you're not. You might want to play at a quieter level, but that's a different issue. Leaving is always an option but IMO there would have to be another, more important, reason other than being "too loud" for me to leave a band.