I have a Roland Cube 30 and a Peavey Classic 20. I've use both for home practice, and in live band situations. If the venue is too large for the Peavey, I just mic it. I have even put it at the front of the stage facing like a monitor and mic'd it up. It keeps the stage volume tolerable for everyone. I'm not against big amps, heck, I played for years through an Ampeg V4 stack......but my hearing also suffered for it. And this from Guitarnuts:
There is absolutely no venue that requires a larger amp and cabinet than one suitable for use as a stage monitor – provided that the members of the band don't get into a juvenile competition to outdo each other. Need more feedback? Fine, move closer to the amp, for crying out loud! Typically, a really good 30-watt rig with a suitable cab is ample! Depending on the composition of your band and the variety of venues you play, an even smaller rig mic'ed to the PA and then pumped to stage monitors may be even better. Note that while a good 30-watt rig has ample volume you may end up having to buy a more powerful rig to get other desired features.
At a small venue, a 15 to 30 watt amp can be placed behind the band in a traditional position and used without a mic. In this position the rig serves as a monitor for the guitarist and as the primary amplification for the guitar.
At a medium venue, the small rig can be placed in front of and facing the guitarist as a monitor, and be mic'ed and run through the band's PA. The band's PA speakers are placed along the front of the stage and facing out. This arrangement allows the sound to be balanced at the mixer and allows the band to flood a medium to large venue without damaging their hearing.
At a large to giant venue, that same small rig can be arranged much as described above but now the band's mixer feeds the house PA. This is the only way to reach the back of the room without dangerous SPLs near the stage at a large venue and would be required no matter how powerful a rig the guitarist has.
Smaller equipment takes up less space on cramped stages.
The money you save by purchasing a smaller amp can fund a nice power conditioner to protect your equipment and clean up powerline noise – the conditioner will cost less too since now you don't need one that will handle a billion watts.
If the band members will agree not to compete, all of them can recognize significant savings by not having to purchase unnecessary equipment.
Your band is far more likely to be called back for a repeat engagement if you provide a well-balanced, easily managed performance than if you are just obnoxiously and uncontrollably loud.
Many guitarists already have the monster amp – it isn't necessary to get rid of it. You can use an attenuator (see the attenuator myth) and perhaps a smaller cab.