I'd say that the GE:S beta is farther along than the PD:S beta. What little of it I tried, it didn't seem very polished. My Windows install is pretty boarked right now, so it's hard to tell, but PD made Source crash more often. I don't know if anyone plays PD:S, cause I saw no one on when I fired it up. PD could get popular if the alpha was out before GE's, but I don't see that happening. The PD crew needs to just hammer out the guns and maps first (which are it's strong points), and leave finetuning the player models for later. All I gotta say on that is someone spent too much time making Joanna's fists...who give's a crap.
Plus (not that I'm even tempted in even the most minute amount) isn't there a Perfect Dark game out for the X360 that you can play online right now?
Another slice of hope is that Nintendo is starting to allow developers to release original content on the Virtual Console. Depending on if they can do it legally (contract with MS), I would love a slightly revamped version of Perfect Dark 1. They might be able to fix the framerate issue, and add online play. That would be cool.