I have at last got my sticky fingers on my sparkly new iMac and the screen bit is really good, also the machine just zips along at a fair old clip and everything seems very much quicker in use and even Lr opens in a few seconds.
I managed to get everything back due to having a Timecapsule backup it never lost a single file, super! Only took 5 hours to get up and running with the migration utility!
I think one benefit is a clean install of El Capitan helped, but I did forget not to update Lr & Ps, hey ho.
Twelve days of not getting any updates led to lots of updating when the machine was running, only took about an hour to get them onboard.
The species as follows:
IMAC 27"/CTO
PROCESSOR 4.0GHz QC i7, TB up to 4.2GHz
MEMORY 16GB 1867MHz DDR3L (2x8GB)
HARD DRIVE 2TB Fusion Drive
GRAPHIC AMD Radeon R9 M395 w/2GB
MOUSE Apple Magic Mouse
KEYBOARD AND DOCUMENTATION Apple WL Kybd+User's Guide-B COUNTRY KIT COUNTRY KIT-B
Just need to pay for it now.