After much thought I decided the “second” computer (which is actually the newest and therefore fastest) will be used for the maps that I draw and the “first” computer (older) is the one I use for my study and some work as well. So the second computer now has the quad head video card and three screens on it and the most memory (currently 16 GB but it’s going to be increased to 24 GB as it is capable of having 32 GB installed). So finally I have worked out how best to use the available computing resources I have in the best possible way. 2nd computer has also had a keyboard/mouse slide installed into the desk that it sits on and the desk has been moved to make it easier to use.
The allocation between the two computers is driven by having a suitable study location where there is less road noise in the house and also making sure the computers are both being used. It helps that the 2nd location can be heated effectively with just an 800 watt radiant heater, often at only 400 watts, otherwise the 1st location would have to be used for everything in order to save power in winter.
Since I was mostly using one computer for everything the resources needed for that one computer made no sense to all be concentrated on one computer when the second one is available. The second reason is having the scanner and printer in the same room which also means I only need one Windows PC in the house, as described below.
The bedroom computer is running Mint 17.3 and will be staying on it for now, while the lounge computer is being updated to Mint 18. A key requirement for any reinstallation is picking up the RAID arrays that I use for the home partition hopefully without having to rebuild them from scratch. Here I am assuming MDADM can assemble the existing array back together so that Mint recognises it. Rebuilding would require everything to be taken off the disks because they would get wiped. Since the scanner has been moved to the lounge, it can connect to the Windows computer in there which means the bedroom doesn’t need a Windows computer alongside the Mint PC so I can go back down to three computers in total.