Tombstone: This needs some altering so that it can be used on Solo. Doesn't even have to be the same effect. In WaW Quick Revive did nothing in Solo, which was thankfully changed. I would actually like to see the Perma-Perks (the one where you keep your perks after going down) Persistant Upgrade be integrated into for Solo. It would be useless without Quick Revive, but if someone wanted to keep their other two perks they could go for that combination.
It was also the wrong map. Because TranZit is in sections, you'd always spawn in the wrong section if the white player wasn't in your area. I'd like to see appear on a smaller map. Tombstone would be great on maps about the size of Moon and Call of the Dead. Who's Who: This perk was troublesome. I felt like it clashed with Quick Revive. And I still don't even know if Quick Revive activates if you run out of Who's Who time.
The inconsistent spawning locations. It seems like 3arc just made it so you spawn in the general radius of your down. Which is bullshit. They should've had set spots where you spawn at (I believe they have that for round respawns too), so that you know where you're going to spawn. And how you can plan to get back to your body. But also so you wouldn't spawn in bullshit places like this one that happened to me.
This perk was also on the wrong map. Because of the many different levels, you would rarely ever get to your body in time or you would die trying. Great on a small map like Nuketown. Electric Cherry: Great perk, would love to see it return. The combination of it and Speed Cola, or having an Insta-Kill was great. I'd like to see it get a jingle eventually. Not really much else to say about it. Vulture Aid: I like this perk. The scavenge effect is amazing. This actually makes low ammo/single shot weapons like Shotguns and Explosives actually somewhat viable, since you're replenishing 2% - 5% of a weapons max ammo with each ammo scavenged, compared to under 1% with Assault Rifles, SMG's, etc.
The sight thing is nice, but I felt it was only put in since you were underground and couldn't tell where the box was. It's not really needed for wall weapons or perks. Though the brighter zombie eyes was a nice touch I appreciated.
The green smell cloud I feel may have been a little OP, at least on Buried which was already an easy map. I would like to see time the cloud remains dropped to about 5 seconds. I think that gives you enough time for a quick breather, but to also still be kept on your feet.
Regarding PhD, I have a feeling that will be changed similar to Double Tap. I don't think it will be gotten rid of, but changed to accommodate sliding. Possibly also tweak the explosive immunity a little. Not get rid of it, but maybe change it so the immunity only last 5 seconds once you begin shooting your feet. Literally that was the only reason it was missing from BO2. When it did appear, you easily lost from fall damage, or M&S just weren't in the map. So I would be okay with a timed explosive immunity if it meant it came back.