plastic or metal WH catch pan?

I would think plastic would be better, but at HD the plastic pan was listed as for "electric" and the metal plan was listed as for "gas or electric".

What's the theory behind the distinction, and does it really matter?

In theory (mine anyways!), the base of a gas WH could get hotter than an electric because of the burner. On an electric, the heat is higher up and surrounded by water. Some plastics can handle quite high temperatures, so I don't know if it really matters...just depends on what it's actually made of.

Plastic / electric...metal / gas or electric...a flame could melt plastic