Agree with Rod, although the Super Bassman and V4B are not smaller and more portable than what you have today. I wouldn't count the V4B out. I find that amp to be surprisingly loud through the right cabs (I use 412s now). For the type of band you're talking about, it would be perfect for me. I like both amps for different reasons though. The Super is huge, warm and fat sounding with lots of tone shaping options - crazy power on hand too. It can stay clean at very high volume or be dirtied up with the second channel. It's amazing.
The V4B is 24lbs lighter, much simpler to use (for me anyway), dead quiet (no fan) and perhaps a sweeter tone than the Super. Cheaper too, if that matters. My favorite trick though is that it stays clean enough, long enough to keep up with the old school country and blues we play. But when we start to get into the Allman Brothers/Skynyrd, etc stuff later in the night our volume creeps up and that head starts overdriving in a magical way. I've never liked buzzy distorted bass tone - but my God the nice, warm, rich, creamy power tube overdrive is heavenly. The drive from the second channel of the Super is amazing too - a different flavor of awesome.
So it's a toss up between the two for me.
I've never been happier with cabs as I've been with my 212AVs. Super warm, well balanced, light weight (for ceramic loaded cabs). They have really great low end, but remain tight. I guess they were going for a ported cab that paired well with tube amps and they achieved that beautifully. Kills my GAS for anything else.