Have a Slacker, never laid an arse cheek on a BFe.
Slacker is a cheap/good value frame with plain gauge tubes and super slack head angle. If you go for a double+bash and run a bigger double ring (say 34 or 36t) then the chainstay clearance (with the intended 50mm spacing on the cranks) is fag paper tight. Not a massivey big deal but has lead to a few jammed chain problems. Price of being able to run big tyres I guess. Apparently you can “squeeze”/deform/crush the chainstay so clearance is better.
The tubes are regular old DN6 / 4130 cromoly equivalents (I think :-S
Personally went for 16″ at 5’10” and found it good. Bit short for climbing / general riding but manageable. Really good with the saddle out the way or when doing tech stuff where you’re moving around more on the bike.
Thought the BFe was (unkindly?) referred to as a Soul with more meat on it. Glancing at their site the HA is much steeper than a Slacker. 853 tubing as well by the looks of it. Oh, and 3 or 4 times the price.