The whole "heavier is better" approach is more of a macho thing, I find. I personally always thought lighter strings sound way better for Metal: Crunchier, more lively, tighter, more cutting, etc. While heavier strings just sound duller, thuddy, boomy, and bland. It's just that I have a hard time personally playing strings too light too, so I try to find a happy medium for me.
JMO, of course.
But 11's will be fine both sound-wise and feel-wise for Eb.
I use 11-54's in Drop C on my Fender and 12-56's for the same tuning on my Gibson.