I thank you for that quick and comprehensive reply, even added coverage of things of which I had not thought. I am trying to anticipate problems this time, hence these questions.

I mainly anticipate the dual extruders to be used to have a separate extruder for support, but having just watched some videos of the dual heads working independently to double work flow, I can see the benefits. Quite amazing. I was forced to used Simplify3D to get access to a larger nozzle size of 0.6mm to suit the T-glase. That was easy with my old Leapfrog, more challenging with the Makerbot with models 14cm square and highly detailed. The ability to produce two at once back then would have been great. I can see windows opening.

My concern is my lack of familiarity with that surface, compared to glass and hairspray.

My queries have already revealed the vast array of new filaments, it is a whole new world compared to my early days. I may need a filament cabinet as well.

Thanks again
Bob