The PID tuning was all good, and the bed did take a while to heat up and cool down. M500 did the trick to save the settings run for hot end and heat bed. Then I noticed the config-override.g popped up in the system file. Have been wondering about this for quite some time as there was a lot of mention about it and I was scratching my head over it being missing.
Fiddly with the extrusion steps at the moment, and my previous steps were way off! Or maybe it depends on the filament and the individual machine setup. But 813 steps mm for my Titan aero setup seems to consistent after a couple of test runs.
Cheers for the hints and tips as I get a bit closer to a test print. Hopefully these 3am tinkering sessions will come to an end soon 
Will need to setup this huge printer again on my new PC. Will jump through the hoops and try my best to optimise and tune it to do those big prints again.