I’ve also compared a few times my 72 SuperLead 100 and ‘89 SLO. I found the 72 was more raw, brash, open, punchy/hard hitting, and more mids like you said, while the SLO had more lows, saturation and a unique, pleasing quality in the uppermids that I can’t quite get the same way in others amps. I find SLO’s to be more of a smoother but still bright amp rather than bite-y. I haven’t tried a BAD era version though
Just a terminology thing, but Marshall’s went from plexi to metal panel somewhere in 1969 and seemed somewhere around then to take on that more more brash/hard, brighter character. The Plexi’s I’ve had/still have and tried don’t really have that hard Marshall kerrang often talked about on here. The Friedman’s remind me more of the ‘60’s Plexi’s voicing and I always thought maybe why they don’t do that kerrang thing either