Contrary to common belive, acrylic sheets make an excellent build plattform for pla, in fact, i only use bare acrlylic sheets for all my prints now days. It is a bit of a learning curve, and not all acrylic sheets are of the same quality, but when you find the ones that works, say good by forever to all cinds of tapes. Also, when the print is done, i just pop out the sheet, bend in slightly in different direction, and the parts almost pops of by them selfes. However, using the replicator 2 acrylic build plattform is not a good idea, simply beacuse A: Its not made for it and therefor probably doesnt have the optimum properties for it, and B: its specially made, and therefore cost more to replace after wear and tear.
I use a Replicator 1 with my own addon in order to be able to use 3mm thick acrlylic sheets cheaply bought at any hardware store. You can find this addon at:
http://www.thingiverse.com/thing:32057. Sure, this is designed for the Replicator one, but im sure you can modify it in order to make it work on Replicator 2. Good luck!