Just to let you know Martin, when I re-set to Marco, the desktop threw a fit again and I lost the capacity to navigate with the mouse as well as losing all window titles etc. Cold boot required again. At which point all working again under Marco.
All in all, this version of Compiz, at least on this particular machine, is a quite a bit worse than the standard version of Compiz I installed from the ordinary repos when I first installed Ubuntu Mate on this machine a week or two back. That version was a bit flaky, but not as bad as this. Like I said, though, it may just be a function of this particular machine’s hardware configuration and this version of Compiz might be okay on everyone else’s.
Will be sticking with Marco for the time being.