I haven't personally run rubbers on my car at our track, we run open tyres (rubber or foam) with no additives so foam is faster (all other things being equal).
I'm 99% sure the foam is a lighter rim/tyre combo than rubbers, I normally start my foams at 60mm and go down to about 56mm, after that they start to slide around too much and are hard to drive.
I just had my first race meet on the weekend with the TC5, and the car really wasn't good at all, with us running asphalt with foam, and a 12turn motor limit I'm really shooting in the dark on setup (the car has only prob had 20mins total track time mind you), so I will be interested to see what setup you come up with on foams, I'm still experimenting.
/edit, I was going to hold off using my ITF main chassis plate on the car but I think I may have to, my FTTC4 loved it and the TC5 is exhibiting the same traits the TC4 did with the stock stiff chassis ie. very nervous and hard to setup