Hi Dave
I have had the JMI 15 with blue alnico for a few years now.
I have used it for almost every gig, with two bands, including several shadows tribute events i Denmark and sweden.
Quite often other guitarist use my amp, if they like, and everyone, or almost everyone like the sound.
Compared two the regular AC 15, with different speakers, and even the vintage series, it can play bleeding loud.
I was lycky to buy mine second hand, as the new Price was very high end.
Like all other equipment, you could consider if the higher Price gives you the same better sound.
Though I have heard all the bad stories about the Company, I have had no problem with mine, only ever changed one tube.
Regards
Niels