Amps are made of resistors, capacitors, tubes, transformers, etc. I have a vintage Vox 61 AC-15 and a 65 Vox AC-30. They go for months or years without breakdown. I do a few shows a year but log lots of studio and practice hours. I usually need a repair every 4-7 years. Last time a cap only.
Plus, the vintage Vox will go up in value. There are several good boutique amps, but most of the best only partially approximate the tone and compression from a good or great vintage amp.
Boutique guitar builders exceed the sound of many of the best vintage instruments.
The Marsha is one of the few boutique amps I've heard in some time that rivals/equals or surpasses good vintage amps.
Also the TopHat Ambassador line out-blackfaces a Fender blackface. Many of you can chime in on other examples.
The JMIs are chimey but harsh and very stiff sounding. They have vintage tone but the compression is not there like on a Vintage Vox. They are overly bright which overlaps somewhat with the harshness factor.
Did you try them with Celestion Blues or "JMI" fanes? Big difference