The PTX3 is no longer made, the Current Prodigy remote is the PLX3.
The MC3 is a 'Full' Crestron processor that looks just like a PMC3, has all the same inputs and outputs, and supports all of the latest Crestron software. I.E. Smart Graphics and Simpl#Pro(You don't need to know what that is, so don't worry about it)
Depending on how the PMC2 was programmed it is as easy as a right click or a few clicks in some menus to change the program.
All of these products are available though authorized dealers who should also be able to set them up for you.
Note-to use a 3rd party remote you will need to get a Crestron RF Gateway, an RTI or URC remote, a Crestron Processor and someone to program all of this equipment for you.
What is it that you do not like about the remote?
It is possible that if it is the PTX3 the UI used was just poor and a newer UI/GFX could be created
