I don't get the argument that OKW NEEDS the Puma. It has shrecks on a durable, cheap unit. The Raketen actually does its job if you aren't on a hilly map. The Jagdpanzer is an excellent tank destroyer that can beat IS-2s if supported a bit and shits all over medium tanks that can't flank it (hello shrecks). I never have any problem fighting off medium tanks as OKW unless I've been pushed off the map and denied fuel. The Puma just makes it even easier, properly microed you can need no other vehicle until you break out the KT/Panther/Jagdtiger. Hell, I'm pretty certain OKW actually has the best non-doctrinal midgame AT of all 4 factions. Raketen is not as good as other AT guns, but requires no teching, can garrison and can retreat. Once it's tendency to fire at the ground is fixed it's a fine unit.
I mean, going from playing OKW to US, it's incredible how different they are. US is a faction that has absolutely shit midgame AT. All you have are bazookas which can't pen anything bigger than a StuG and cost fuel to get, AT guns that you need to spend ammo for them to be good (and massively delaying your teching to T4 in the process of getting them), and... that's it. Stuart is only good for its abilities, I'd trade it with the Puma in a heartbeat. Until they get the micro-intensive Jackson, US AT in general is far inferior to OKW's.
I just don't see the problem. OKW is in my opinion the last faction that really needs a unit like the Puma. Doesn't mean it should be removed or anything, but a small nerf wouldn't hurt it overmuch. Just nerf its penetration a bit, it should be a flanking vehicle, yet it can reliably pen the frontal armor of medium tanks that come much later.
The midgame AT capabilities are not the only feature which make the Puma such an indespensable unit for OKW. It's also basically the only armor OKW can field til late game. Jagdpanzer is too situational and expensive to go for it, it'll cost you games when facing inf spam tactics. Flak HT is run by clowns right now. And thats it. Puma is the only way to be offensive in OKW midgame, forcing the allied player to deal with armor, fighting weapon teams, snipers etc. Its basically the OKWs allround medium tank with lower AI abilities to compensate for its early availability.
Without any armor on the ground, and the Raketenjoke, OKW wont be able to survive til late game.
US is a whole different ballgame. In the US OKW matchup, theres not much armor to deal with for the US player until lategame, and then he has tankhunters + at guns + zooks. I cant speak for the OH matchup though cause I lack experience. But I'd generally say that having a viable AT gun is always a safety net. And how is 270mp a "massive delay" of your tech? Its a cheap insurance for any german medium armor coming along. Or are you the one player worldwide who's playing without a Captain?