Moving from Magnepan MGIIIA to 3.6

It may be time to think about trading my beloved MGIIIA up to a pair of the 3.6's. Anybody here make that move? Is there enough of a difference in a positive direction to warrant the expenditure? For the record, my III's are in great shape in both cosmetics and sonics. I am the second owner and the ribbons were replaced when I got them in 1994.
The rest of my setup is listed under systems, and my amps are up to the task of driving the 3.6