Quick update: we somehow have managed to go backwards to regular 45min wakings in the night. Last night he went down at 6:40 following PUPD then woke 45 mins later.
This is classic OT. And it likely played a part in the other NWs as well, but I also wonder if there isn't some discomfort. That's a lot of wakes throughout the night.

Is he getting any teeth or eating new foods that could be upsetting his tummy?
I read a forum post today that mentioned putting them down straight after picking up and saying your calming phrase, and not waiting till they calm in arms?
Yes, at this age you really don't hold them for long, I'd say a minute tops if he is quite distressed. But, otherwise just say your sleep phrase and then lay him back down. If you feel like you are becoming a prop and PUPD is working him up more than teaching him to self-soothe, you can certainly just settle him in the crib. You can always try shh/pat or a variation like rubbing his back while saying your sleep phrase or singing a lullaby. Or just sit next to the crib and hold a hand on him, pat him, or pat the mattress next to him while soothing him with your voice.
Should I hit the pause button on PUPD and try and work on his EASY? Or press on with PUPD?
If it were me, I'd continue on with the PUPD (or whatever settling method you choose), while working on the appropriate EASY. I think that if you go back to a prop for getting him to sleep, it will likely be tougher the next time you try to get him to settle independently. But, it really is up to you... if you think a break will do you all good, then take one. Is there a way to get him caught up for a couple days by doing some stroller/car/carrier naps and then going back to working on PUPD? If the naps happen a bit more incidentally rather than with the old prop, it may not set you back all that much.
All my friends keep saying let him cry and I keep saying no :-)
Finally, (((hugs))) for this. Nothing worse than to have people urging you on to CIO when what you're doing is hard. I can assure you, it does work though, and you'll be so glad you never let him cry as that often doesn't work. I think it's just a matter of tweaking your method and your EASY to get him sleeping better.