When it comes to keeping up with a drummer, talk bass is quick to recommend 500+ watts and 2 12 cabs.
I live in a college town with many alt rock and punk bands. In nearly every band here, the bassist is using some sort 100w 12in combo without pa support. Hearing the bass is rarely an issue. These bands are loud and the drummers play hard.
Even in the largest bands, a Rumble 500 can be heard in the mix with 2 AC30s.
A small combo isn't going to get you the best tone and heft in the mix. And it's not going to compete if you're guitarist are painfully loud. But in most situations, you'll be fine, especially with pa support.
I think the members here way overstate the actual power needed for a gig.
If you have a big rig, your going to sound better in a loud band. If you only have a small amp, go uses it, you'll get by