Comparing Generations of Equipment

Sports people love to talk about how Babe Ruth would do with the current athletes or how some of the 60's tennis stars would do on today's tour.  For audio people this comparison is much easier if they can hear both the older and new equipment.  Does anyone do that?  I am surprised the magazines have not jumped in on this, since despite the hype, most product innovations are incremental rather than dramatic to my ears for models released every 3 or 4 years.
 
How far has stuff come along in the last 10 or 20 years?  Is it incremental or huge?  I am especially interested in how some of the top of the line stuff of yester year compares with the current models - both at the high end and at the middle part of the line up. 
For example:
- How does the watt puppy 4 compare with the Sasha? 
- How does the original Wilson Maxx compare with the latest Sasha? 
- How does the older Reference CJ gear compare with some of the middle of the road CJ stuff of today or that of other brands?
- How close is the old dcs stack to some of the recently released sources?  At what price points does it compete?
 
Also, do the prices of used equipment correlate at all with the sound quality, or is mostly based on brand image?
 
Thanks!