the thing that makes me cringe about vietnam with arma is the AI ... i dont think their new engine actually fixes any AI stuff and is mainly a graphics upgrade etc etc
Yes, there's indeed a problem with Arma's AI and jungle environment (for example they can see too well thru grass and vegetation). Of course one would expect that a tentative Arma 4 would solve such issues but then again we're talking about BIS...
On the other hand things seem to work rather ok regarding Tanoa, which would be rather similar to a Vietnam scenario.
a 60s/80s era african "bush war" would be pretty interesting, you'd have everything from ww1 stuff to modernish 80s to potentially place with!
Actually, I believe you could be surprised that with such conflicts you could even have much older weapons than WW1 stuff.
For example, an uncle of mine served in the Portuguese Army in the Colonial War in Angola and was deployed in the southern part of Angola where he saw action mainly against UNITA forces where most of its forces at the time were armed with Flintlock Rifles (mostly using nails and sometimes together with shards of glass as ammo) and even Bows and Arrows.
By the way, my uncle feared more the Bows and Arrows than the Flintlock Rifles.