You barely can imagine, how concretely I know about what you're speaking.
During the time I'm building tube amps (more than 3 decades) altogether I've had 7 or 8 original Dumbles in my house - and moreover I've had uncounted Dumble clones of all coleur (VanWeelden, Bludotone, TwoRock, BrownNote, Fuchs, aso.) in my house. After this all and although all of the cloners (more or less) have cloned the orig. Dumble circuit, the layout, have used the same components, even the same transformers (at least the OT) I honestly can say, that nothing compares to an Original.
Don't get me wrong, the Dumbles I've had in my house didn't sound all the same spot on - no! But (sorry I'm a German and I don't have the right words) all these Dumbles did have something in their sound, this special kind of chirp and tonal charisma, moreover that kind of playing feel they gave me by playing through it...
... such a distinctive character, what I couldn't get out of any of all the clones.
Again don't get me wrong, the clones throughout didn't sound bad, quite the opposite some did sound really great by their own, especially the VanWeelden and the Bludo... but you could hear (and feel) with closed eyes and with your back to the speaker cab - no, this is not a Dumble.
Your "and should be considered at least 5D lol" made me smile and gave me the idea, that you maybe should ask sBlue how many D's he'd give his Larry British Purist.
You've already read his initial post in this thread:
https://www.rig-talk.com/forum/threads/nad-larry-british-purist.209276/
What I still could add from my side is as follows, picked out of the user's manual:
"WARNING: Though the BRITISH PURIST TUBE AMP by LARRY isn't an overly aggressive or angry sounding Heavy Metal Beast, nonetheless it's the most powerful, dynamic and 'into your face sounding' amplifier of the Larry amp line. Hence not unfounded some guys already named this amp 'The Earthquake Generator'."