I have a bunch of amps: Orange, Bogner, Vox, Peavey, and have had a pile more, but my ysr1 (which I believe is a 1967) has stayed as others came and went. I actually built a 212 combo box for it to Bluesbreaker dimensions. My understanding is that they're similar to a JTM45 with a trem circuit, which I also understand is what a Bluesbreaker is. Mine doesn't really have the dirt that a BB spins up, but it takes pedals like no other, has lots of headroom, and does get into old Marshall territory when you spank it.
My ysr1 will never go anywhere, if it were stolen I'd get another one, and I'd support anyone who was thinking of getting one. It's top notch!