I wanted a Drell Adept so bad and I got one in my recruit pack!---he's horrible. I really don't like it. What's up with the grenades? He's twirling way too much---just not for me.
The easiest way to deal with pyros in my experience is to wait behind cover in the path they're walking then do a melee grab. That or keep overloading/draining/incinerating them because they'll stop moving forward.