Decorations with UGH

I was reading in the "Aquarium Plants Manual" this weekend, and Schuermann (sp?)
mentioned that one needed to be careful when using rocks with UGH.  He said
there was a potential of heat build-up under the rocks, and the possibility of
cracking the bottom glass of the aquarium.  So, those out there with UGH, do
you use rocks, or driftwood mounted on slate, etc...?  Have there been any

In a related issue, it has often been mentioned that a sheet of thin foam (1/4")
inserted between the aquarium stand and the aquarium would help the aquarium
"self-level" itself, and also provide some insulation.  In a tank with UGH,
is this added insulation a good thing or a bad thing?  In light of the above,
would this add to the problem of heat build up under decorative rocks &

Thanks -

David in Atlanta, where currently it's *really* humid & foggy.
david at joshua_medimg.emory.edu