MarcM, I am in a similar situation. We also bought the additional acrylic cover in order to retain heat for difficult-to-print materials, fully expecting to be able to use it (and the new improved aluminum build plate) to print 'challnging-to -print' materials like PC. Without the improved build plate, we would have been MUCH better off purchasing a less expensive (but no less capable) printer.
I think it is the obstinate position taken by Ultimaker that this decision to cancel the aluminum build plate is no big deal. That decision is truly in the eye and mind of the ($6k USD p