Modern Versus Restored Vintage SS Amp Sound Quality?

It depends greatly on the amps. My Thresholds SA/1 or Krell KSAs are great amps even compared to modern amps. Old tubes are also good. Old SS mid level gear will likely not compete with modern amps.

problem transistors replaced...

Good luck finding those for old gear. You blow the transistors and most stuff is junk. 

General knowledge: Mass market vintage equipment was not that good. There are exceptions but they are rare. There is so much really good modern stuff it just doesn't make any sense to put any money into repairing old gear. 

I'll post up a 2022 PA5 against any 'vintage' Jap ware.

Vintage glass good, vintage sand bad.

I've been down this road and in my experience vintage can be great but like others have said its depends on the kit. 

I personally like the Sansui professional series. recapped etc they sound very similar to modern SS amps with a little more warmth but a little less over all detail. 

I Also like early vintage Luxman specially their class A amps from the about 78-84. L560 for example is wonderful and modern sounding. 

there or many others but do your research as there is a lot of mid-fi crap from those days as well.  Also many of the hi end stuff from the 80's are now vintage and could be a great find, early Krell, Classe A, etc. 

I'd honestly say there are better early tube gear than early SS gear as a whole.