Very cool, certainly very hyped for it. While I did love the human classes quite a lot and feel like Mr. Green's ZS server was the one that ever really got human classes perfectly well done in ZS history. (And it's the only thing I'd love to see coming back in some form or in some place within GMod itself, really.) The gungame system ALSO really made it much more thrilling than your regular modern ZS. Either the good ol' L4G variant or Classic Edition/Redeemed Edition are gonna be waaaay better (doesn't matters which) than modern Zombie Survival, it is why I am going to make sure to tell a lot of people about what's happening, this deserves to get attention and be able to get popular, I have very fond memories related to this server's gameplay and I really would love if ZS Classic, whether through Classic Edition or not made an eventual comeback.
I can't wait until I can try the gamemode as it once was, back to the simple old days when it was really all about having fun. I never got to play on Mr. Green's ZS server before human classes, but I did play ZS Classic in a different community before that, and I can safely say that plain, Classic ZS is one of my top two varieties of ZS as a whole, and I will be so happy when I can finally play on it once again!
For me bosses pose a problem when it comes to balancing both the human and zombie team in so many ways. And yet for me arsenal crates (arsenal crate shop with points and all that stuff to be specific, the Green ZS crates were fine for me.) pose a problem when it comes to actually having fun and keeping it simple too.
I'd definitely be interested in the good old cosmetics as well as new ones too! As long as they don't feel too out of place it's definitely a thing I'd give a warm welcome back to once more. I believe achievements would be on the same note as well, and unlockables do sound like a lot of fun, definitely wouldn't hurt. The simple things like the very distinct HUD the server had, the different Half-Life 2 quotes that the playermodels spoke out while reloading or just walking around or even spotting a zombie, those quotes I mentioned I believe came around 2010 if I remember correctly based on what I've been told and what I have seen, but those are a couple of little details I'd love to see here too! The distinct visual effects when you were poisoned or a Wraith/Ethereal screamed close to you at one point. All of that made Mr. Green's ZS server really stand out from the rest in a very positive way when it comes to the gameplay formula that it followed through it's Classic ZS-2010/2011 L4G ZS era. I'll be honest with you, I personally quit back in the day once the modern arsenal crate-like system got added. (Using points to buy guns and all of that.) And I didn't do it out of anger of course or anything like that, but because back then I simply felt like I no longer had fun in the server after seeing that if I am very blunt about it.
Over all, I trust that the end result of this journey will be one to cherish, and one that'll be just like the original!
P.D: I do really hope that at least the cosmetic part of the server (visual effects/models, audio and all of that) bit will be added from the 2010 to 2012 era, as far as I remember, it all looked really good, regardless of whatever route this gamemode and whole project ends up taking.