This site wants to have it Both Ways:
http://www.premierrange.com/faq-aluminumfoil.htm

"Aluminum foil can affect oven performance if used incorrectly. If desired, a
sheet of aluminum foil may be placed on the floor of the oven UNDER the bake
element. Be sure the foil does not touch the bake element.

Do not line oven bottom with foil or other liners. It could affect the quality
of your baking."
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Pfft! A lot of help You are !
Nancree (Pulling her hair out in frustration)


A lot of help YOU are! Pfft !

I say line if you like. The foil will help to keep the oven easier to clean. A clean oven reflects heat inward... Why waste energy heating up the bottom of the oven any more than necessary...

I have stainless and enamel roasting pans. Believe me the color makes a difference in the way a roaster cooks. The oven finish could do the same I suppose...

I guess a nice dirty oven might be less likely to burn the bottom of a cake...