On the off chance you see this, I'm pleased to report that the answer is, no! It works brilliantly as long as you use the free "Parsec" service's client to access the desktop and your games. Browser access to the Paperspace desktop is fine for normal app use but no good for gaming.
Setup wasn't quite push-button but I got it up and running by dumbly following the instructions. Parsec was the most confusing part. Trust the docs, and it'll work.
Mostly older FPS multiplayer games against friends. Garry's Mod, the Source version of Counterstrike. Haven't seen any issues at all, really feels like it's on local desktop (other than the quite obvious graphical degradation in fast-moving play). I have a hardwired ethernet connection to my router though; I bet it'd stink over Wifi.
Also - am not good. :)
EDIT the latency figures are nothing like 50ms though. Low tens maybe, total. This isn't a huge surprise though: on the same machine and connection I've also (using JamKazaam, not over Paperspace) had decent success doing online realtime music jam sessions with local friends too, where the latency tops out around 25ms - can't really get into the pocket playing funk, but just fine for rock.
Setup wasn't quite push-button but I got it up and running by dumbly following the instructions. Parsec was the most confusing part. Trust the docs, and it'll work.