KEN - In the case of Kohler gas tanks, the gas is free to circulate from one side to another. Gas is free to pass from any section to any other section. I think the new plastic tanks are all one piece, blow molded plastic and no internal baffels or partitions. I really haven't taken the time to peek into my new tank on the 72. It's REALLY dark inside those tanks.
The thing that KILLED production of steel gas tanks was the TERNE COATING the manufacturers had to use to protect the inside from corrosion. Terne coating is 10-20% tin and the balance is lead. I've heard of TERRIBLE things happening with companies trying to cheat on quality, and galvanize, zinc plate the inside of tanks, and especially on diesels, if and when even a small amount of the zinc goes through the injectors they will be ruined.
I've never really had a problem with corrosion inside any of my home-made mild steel gas tanks. I normally run a shut-off valve and a Mr. Gasket clear pyrex sleeve in-line gas filter on all my Kohler powered equipment. They use a molded nylon filter with openings so small even water can't get through. No chance of any kind of dirt getting past them. And you can clean them and reuse them. Summit Racing, $14.95 each