There were a lot a problems with the PMA-5 unit. To name a few - there were a lot of intermittent problems with the MIDI IN/OUT connectors and even the line out/headphone jack over time.
They were truly revolutionary and awesome. I would not trade mine either. I write more songs on my PMA than on my workstation - which is a shame.
When I get stuck on a song or am trying to write a new one I grab my AX-1 and my PMA-5 sit on my back porch and play.
Roland recently dropped the proce to $280 to clear their inventory and there are some around.
I agree, the PMA is much easier to use than the QY-70 and has just the right amount of functionality without trying to take the place of a synth as the QY-70 does in some instances.