Any 1000lb bomb on a fighter in EWA and MWA?
4k cookie in lancs in EWA?
When was the 6-gun package on the F4F-4 introduced?
I don't know about any others off the top of my head. The major ones that came to mind were the mix-matched 109 and spits, but those were sorted out when they were remodeled.
EDIT:
To me the biggest single advantage would be limiting ords to 250/less options at small, 500 lb/medium and only enabling 1,000lbers at large fields. That would separate out the "strategic" war and make defending the zone bases more important...
I think it's a server-wide setting, not a field-specific one.