I'll disagree. I've owned a couple JMP 100w MV amps- for everything that the ordinary guitarist is going to be using the amp for- the 50w makes much better noise.
The overall difference in volume between the 50 and 100w amps is barely noticable. However, the tone you're getting at the usable volume range is noticable. IME, the 100w amps- when using the pre low and the balls coming from the power section- they sound great. Much bigger. More "grunt." But when you're using the pre as the gain generator, and have the master set under... say... 1-6, the 50w just sounds better- bigger and fuller at lower volumes. Once you get into pushing the power section- it still sounds great, but I think the 100w sounds better.
THE IMPORTANT THING IS TO THINK OF WHAT YOU'RE USING THE AMP FOR. Right off hand, I can only remember one time when I had my 50w amp wide open. I've played in loud crashy rock bands my entire life. I've been actively gigging for 20 years. ONE time have I ever had my master beyond 5. (outdoor party, vocals only PA, people all around)
Usually, I'll rely on the the preamp for the gain and have stage vol around 2. For most anything you do, any bar you play, most any stage you'll play, a half-stack is plenty. If you really want to put the effort into a full stack, the 50w will push that fine as well.
I can't think of any professional stage I've been on that would tolerate a 50w half stack at 8.