If you are really wanting a plexi tone, feel and response then the Metroplex should be high up on your list with an actual 68 plexi or maybe a 69 metal panel comes close but they have the higher filtering on the screens and preamp which seems to affect feel somewhat. Unless you can find a 68, 69 or a 70 I wouldn't look into later Marshall Superleads if you are wanting a true plexi.
What are real plexi's now pricewise???? $5000.00 - $10,000.00? Don't get me wrong I love my 68 plexi but if you don't want to have to attenuate/ variac to get it usable at reasonable volume levels then the Metroplex gets alot more attractive IMHO.
All that being said my 69 NOS built clone with Heyboer/metro iron sounded almost as good and feel as my 68 Ed spec Plexi with Heyboer Iron and I would put them up to many NOS amps, but both of them have NOS parts in them, like Iskras resitors and NOS Electrolytic caps and Mustard caps.
What is cool about the Metroplex you get the 65/66/68 and modded 68 tones. I have to variac/ attenuate my 68 plexi Ed build amp to get what I love out of it. In those clips you hear Georges 68 being attenuated by the Fryette PS2 versus the master volume in the Metroplex. I hear the Metroplex has a killer Master Volume.
The only other amp/mod I can endorse in a RT modded Marshall or a Marshall build amp by Michael Audette. My 72 Marshall has the Split cathode RT mod in it and it does sound very good and with the stock 4 input jack setup you still have a 2 gain stage Marshall using the regular bright or normal input jacks and the cascade channel when you plug into the far right upper and lower input jacks. It appears Audette has pulled his YT channel I can't seem to find it to post some clips of his latest builds, here's the best I can do. These are Little B's videos if you want to contact him.
Here's a stock 69 Marshall for comparison....
Here's is a Stock 71 Marshall also to compare