do not use the Foam due to the need to lay labourers on boards until it cures !
Ha ha. Can't afford to have labourers doing that!
We only use tongue and groove OSB3. It gives a nice smooth surface to stick our rubber down onto. That is one thing I hate about Epdm. It's so skinny you do notice board lips or if you are installing the stuff near a tree on a windy day then its a constant battle to keep the "bits" off the roof! I usually arm one of my labourers with Boris (our resident vacuum cleaner).
Never tried it but what about floating decks that are just glued together. I'd imagine they would play havoc with base tie in and upstands.