Iv'e not tried a Supertwelve but i used to own a Barefaced Compact and Midget, in my subjective opinion the Berg is warmer sounding (than the Compact/Midget used together) but I'd say it pretty much has a neutral voice, it's certainly not aggressive or mid biased and for rock i do tend to dial in quite a lot of mid range if I'm using my jazz, less so with a Precision. I think they are designed (rather like the Barefaced cabs) to reflect what you put in rather than having a distinct character of their own, but as I say for a given input the Berg seemed to me to have a warm bias so i suspect by comparison to a Supertwelve it may have a more scooped sound. Hope that makes sense.