Bassman has tubes in the preamp - if you're talking about the Bassman 500, not the all tube 100T and Super Bassman.
So the Bassman 500 has a little more tonal options... with the 2 channels
... but DEFINITELY no probs using the Rumble 500,200 etc for gigs.
I've got a 300w all tube Fender Super Bassman which is absolutely awesome, but I use my Rumble 500C to gig with often also
Cool. Good to know. And tone wise the rumble is just as good yeah? The rumble is lighter?