I have a hard time imagining 3 shops in a row didn't know what an E-Type front derailleur was. What those shops probably meant was "you're an idiot, why are you trying to put a front derailleur on a purebred DH bike?"
They said E-type but it had clearance issues and wasn't a great way to do it. Also required me to get a different chain guide set up which wasn't in the budget. I love my f-der on my socom during the winter so I can whip my ass into shape.
If the bike store was thinking I was an idiot I guess they lost out on a sale, making them the real fucktards.