I feel bad about raining on everyone's parade, but here's my $.02. From a formula point of view, the 100W amp is only 3db louder which is barely noticable. That's when running flat out. If you are mic'ing anyway, that really doesn't matter. When you throw a processor in front of the thing, I'm convinced you lose a lot of the raw dynamics which lessens the differences again. When you are playing with a band, you can't hear most of that anyway. The one thing to consider is that some amps sound best when really cranked. Its easier to live with a cranked 50W'er than a cranked 100W'er. Think stage volume and/or smaller venues. You really need to play both side by side and see what's really different. Chris