I just picked up a PDS 2700 which is the Dual Play, it's interesting for sure.
I'll work on the basis that the Dual Play is roughly half the pedal that Multi Play is.
Firstly modulation, it's nice, quite lush, has that 80's vibe to it but I'd say it's quite unique.
The delay is nice and it's easy to operate and it'll pitch shift nicely. I can't get mine to oscillate but I have a feeling that if I mess with the trim pots it will.
Mainly I bought it for the sampler, it's an odd mode on mine the delay has to be on and you hold the left pedal down and it samples the last second or so (depends on the delay you entered), the right button still turns modulation on or off. From here you can pitch shift it and mess with a few things.
Overall it's nice I paid £55 for mine in rough shape and no battery door, would I pay more? Well having tried it no, the sampler is a cool thing but I think and EHX Freeze would yield more usable results and delay wise there are plenty of better options.
There is a lot of hype around the 20/20 because it plays a specific role in a noise/ambient setup. Most people don't need that, if you don't NEED that sampler then look elsewhere for a delay (personal fav for me is the Subdecay Echobox)
But again the above is based on the double play and not the multi play.