Depending on your EQ settings, and how loud you guys play, what you have may work. (Do you cut your bass and boost mids?) Can't that combo run another cab too? If it can find the matching cab somewhere and try it out! I could swear the guy I bought my cab from had it hooked up and running off an Acoustic 115 combo. You couldn't really hear it over the extention cab. So make sure you get a MATCHING cab. If you go that route.
Your such an ampeg whore! I recently got a GK MB212 and its perfect for large and small gigs and its only like 37lbs.
One other option is a milk crate ( not from the corner store ). Having cab up a bit makes it much easier to hear oneself in context of smaller stages.
I think your amp should be fine for small gigs, I use a 115 with some more watts but it's probably not that much louder than your setup. DI is your friend.
Just a heads up I played a relatively large venue on Friday(600+ people) and I'm pretty sure the opening band's bassist had the same amp as you. It was a mkII and had casters but pretty small, sounded fine. DI with no issues. The guitarist played through a 112 and the drummer seemed normal. They played the large venue fine and would sound fine in a smaller setting without DI. I would maybe look for an extension cab for medium venues that don't have good PA support but the milk crate would suffice.