hey, i was going over some of your lessons and it struck me that most if not all of them would be much easier in drop d or if you want all the string half step down drop c# tuning. i mean power chord with one finger and strumming the open string for a D power chord seems much more convenient.
why do you use E flat instead?

well, there´re many reasons.
first, I like to play with 0.10 gauge. so, if I turn to C# strings turn too soft.
second, I like how Eb sounds. I can hear a band who tunes 1/2 down its guitars, (blind guardian p.e.) and recognize at first what they are playing, you know what I mean.
third and last, how u tune, it´s about your personality, your way to use your axe. I´ve been playing with this tuning about 7 years o more who knows, and I didn´t finish to explorer it, and always I´m discovering new things or ways to get my own sound on this.
so, I don´t know if this is right or wrong, but I like it ^^

cheers bro!

Lian