Older vs newer with comapinies like CAT & AI??

#What are some observations out about cost of newer gear versus older.I know that say after 10-15 years you need to worry about replacing Caps etc but when I see a AI Modulus 3 I wonder how much more of the 'oggds" I would get with a 3A.Saw a 3 posted rently for $600 versus twice that for 3A.I hear that the newest CAT "Ultimate" is overpriced.At $3500 used I wonder if one of the earlier variations might be better bet $$ wise.So I gues the issue unless a major change in desugn happens are newer variations of a piece which "evolves" worth it?Maybe a 6922 change over to a 6H30 would be a marked change but again I thought rently about Counterpoint or MFA Melos(one of the designers of this was Bruce Moore who developed Modulus for AI).I am thinking about newer product like Rogue 99 but when I see some older pieces even if they needed some work I guess I am trying to get high value as opposed to assuming latestis greatest.Thoughts?