I am running with aluminum tape on top of my printer's melamine support platform FWIW.
The platform stays fairly cool as a result (just a bit warm to the touch).
If you run cork or some other insulation on your support, and tape or foil on top of that, whether the platform is melamine or aluminum please keep in mind that for the aluminum tape or foil to be effective as radiant barrier insulation there must be an air gap between it and the bed heater, and it must be shiny and kept reasonably clean.
Otherwise it will simply transmit heat via conduction.
I like the idea of an aluminum or fibreglass platform, BTW.
If/when I have issues with the melamine one I will go one of those routes as well.
A different application entirely, but a good explanation of how radiant barrier works-
And another one-
http://www.atticfoil.com/ (I have installed this exact product and it really does work)