Yeah, feedback from FOH isn't likely to happen outdoors. Tame the monitors a bit and job's done, really. Even there it shouldn't be a problem, but you don't have hands free in the middle of a song if it all kicks off, so better to be safe than sorry.
And yeah, the problem with 2-ohm is the current draw - used cautiously it'll soldier on, but crank it up to 10 and it might wave the little white flag. Can't find reference to current or thermal protection in the manual, although no doubt there is some.