don't own any blowbacks anymore. If you just limited it to gravity fed 200rnd hopper ball then any mech would work, like my blazer for instance. The imposition of the hopper restriction nullifies pretty much any firepower advantage regardless of gun type, except for mags with level ten bolts or guns with eyes or low impact bolts like the new enemy.
I'd play a hopper ball tourney like that with either my blazer or cocker. Would be tons of fun, the only difference to me would be not using a 9v or 12v revy.