I think it was a mistake for Lutron to release the QS version before making it compatible with the older versions. It was a very tough sale. Currently, I understand the maestro's can be left in and there is an interface coming out for the keypads.
On the flip side, i have a client that bought a house and wants to add all the dimmers and fans that were not controlled earlier, about 60 of them. Switching him to QS is more expensive, but should be a smother, simpler install.
It comes down to a comparison between HRD-XXX and the HQRA-XXX wireless dimmers.

Anyone have an opinion about the QS RF product and software?