The Acoustic Image Clarus is a great amp.  It's just a little heavier and bigger, but it's still shoulder-strappable and comes with it's own soft case, like the Powerblock.  It costs a lot more though.  However, it has a lot more clean headroom.

For the type of music I play (Motown), I need an absolutely pristine uncompressed chimey tone.  I can't get this out of a tube amp, which is why I prefer amps like the JC-120, Acoustic Image Clarus, or Crate Powerblock.  I have a Silverface Bassman but it still compresses at higher volumes.