Greg, Please don't forget that this forum will be closing. Please use the sonikBBS and the link I have provided from the K2500 Zone.(posted 9165 days ago)I know many people that have K2500's with all of the options including KDFX and have not added PRAM. It is not neccessary but depending on your needs and the way you like to work, it may be needed.
Any objects loaded into memory such as sequences, programs, FX presets, even samples (everything that has a name and a number) use up PRAM. So if you are creating your own KDFX presets and studios, each of these will take up some PRAM.
The amount of PRAM available simply depends on what user objects you have loaded into RAM. If you like to have hundreds of additional sounds onboard, its unlikely that you'll have too much room for sequencing. If you are more organized and perhaps don't want to use the onboard sequencer, you may not need it at all.
Hope this helps, Mike