Insulation and breathing timber floors

Hi all
After ripping out all the floors and sub-floor (lots of it was rotting) to restump, I am now putting the subfloor back in and am researching insulation options. I live in the sub-alpine so while I have the opportunity of great sub-floor access (ha) I want to do a good job of the insulation.
I have been looking at concertina foil batts and they mention that it is important for floors to breath and hence their floor batts are perforated to allow moisture to pass through (away from the floor I assume). Then I was looking at foilboard which I think I like better but they seem to be impermeable so I was wondering what will happen to moisture/condensation.
Does anyone have any knowledge/experience around whether the floor needs to breath and also some insulation faves? So far I have ruled out AirCell as I read it breaks easily but it also might be too expensive. Bulk insulation isn't high on my list either as it involves stapling chook wire under the floor and I dont want rodents in the floor if I can avoid it.
Ooh, another question, my flooring is old hardwood rough sawn planks that go from one side of the room to the other and there is no tongue or groove on these babies - should I be laying some kind of ply sheeting on the joists first?
Thanks everyone.


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