I've posted the following message on the Acronis forums.
https://forum.acronis.com/forum/96054posting here to to make the solution more easily Googlable.
From one very satisfied customer & brand new Pro version purchaser, in recognition of the pain it saved
Here's how the Windows all-in-one Repair fixed my Acronis install...
-------
I was suffering the Install fails with "Microsoft.VC80.CRT,publicKeyToken" issue on a clean Windows 10 install.
I had previously had no issues installing to the same machine using Windows 7 & it continued to work after it was upgraded in-place to Windows 10.
The issue only arose after I did a full reset.
After much Googling, mostly suggesting C++ runtime installs, I arrived at
https://kb.acronis.com/content/14331 -
Acronis Products: Installation Fails with "An error occurred during the installation of assembly" "Microsoft.VC80.CRT,publicKeyToken"
Following the advice, I ran sfc, checked services were as expected, installed every C++ runtime back to 2005, can't install .NET Framework on Win 10 as it claimed it was 'part of the OS', didn't touch the registry sizing as it would be most unlikely to be the culprit on a brand-new installation, registered mfc90.dll
All with no joy.
So, I went to a tool I've used before to get errant Windows installs to behave
Windows all-in-one Repair from tweaking.com -
http://www.tweaking.com/content/page/windows_repair_all_in_one.html(Freeware with a donate/pro option, which is not necessary to use the tool for this job, the free version is sufficient)
Unlike most 'smart system tweakers' it doesn't try to optimise your machine to being 'something super' all it does is makes sure everything is set to 'factory defaults', without breaking installed apps etc. Kind of what a good IT specialist could do, but without needing the college education;-)
I ran every test/fix as the app instructed & lo & behold - Acronis would install & function as normal.
Chalk up one happy user.