For reasons mentioned above I also decided
to do a fresh install of the official Ubuntu-MATE 24.04 LTS ISO on my old
2011 Toshiba C670D craptop. And oh boy, was I in for a bumpy ride.
booting from USB works OK
wifi took two tries to connect
connecting took a long time.
installer crashes first time
journalctl mentioned [FAILED] to start snapd.service
second time it works
I suspect the networkconnection misfire and the crash were caused by either
- not checking for ready but just using a delay time
- or timing out on loading.
That, in itself, worries me a lot.
As I suspected (see post above) the installer itself is indeed a bit of a pig:
it took extremely long time, several hours, for a minimal (core) install. It is glitchy, massive and slow as molasses with extreme GUI latencies.
I know my craptop, it is slow, but i know how this hardware behaves under different kinds of loads:
This installer behaves like a badly optimized pythonscript as if it is instantiating and destroying thousands of objects a second willy nilly while running on an emulator or a non-hardware supported virtual machine.
This, also, worries me a lot.
The daily ISO + updates that I used until now were a very smooth experience. This final product, not so much.
In my opinion the installer has to mature a bit.
I've also read somewhere in this forum that this installer is a snap.
I understand the design decision but practically speaking this can turn out a bit troublesome in some cases.
Anyway, after a bumpy install it runs smoothly. 
I think I also will try this on my Asus F3T (build in 2005). 