I have no first hand knowledge but I would be concerned with differences in weight of the glass vs acrylic.You don't want to throw your speed off.
I personally side with the manufacturer of quality hi-fi gear (and Rega is certainly one) on most choices in design, since they are the ones ultimately to put their name on the equipment - thus accepting responsibility for it. They chose glass for a reason - it sounded good to them. Although I am absolutely certain that the platter material will CHANGE the sound of a Rega, I highly doubt it will improve it. Unless, of course, you didn't like it in the first place, in which case you probably should have chosen a different turntable. It's like putting a record clamp on an LP-12 - if it really made it sound BETTER, don't you think Linn would do (or recommend) it?
My head is spinning at 33 1/3.....