Friday night was four sets outdoors (Subbing for a dance band) -
Ran my Epifani 2x10's stacked on their side -- first time I've tried that (normally, for an outdoor gig, I'd use my 4x10). In a word, it *killed*. I could really hear myself, the band could hear me, the dancers could hear me... It was great. I strongly suggest you try it.
What kind of Epifani 2x10 you own? I stack my epifani 2x10UL (series 1) vertically too, but on top of a 1x15" cab. Just helps so much to have them speakers close to your ears. Made all the difference when I stacked the 2x10 this way as opposed to on its side which made it lower and away from my ears. I could lower my stage volume too.
Im always afraid of my sound being too loud out in the audience. I hear that the bass projects/travels farther or something so the crowd hears the bass more after the projection of the guitars die out. So the guitar may be louder on stage but what the crowd hears is different, right?