I really just don't know... I like the classic Black Knight, bar the weird leg assembly. I don't mind this new Black Knight, bar the leg assembly. I'd really have to see it in person to make up my mind, and I just can't say for sure if it would be worth it over the classic that I already have.
It is a different mech from the original.
IWM and CGL posted the 3D CAD work of the Gunslinger and BlackKnight to show the sculptors are following the artwork as close as possible (possible due to the Dragon II backlash) if someone gave mini skinner legs, chances are someone would complain it wasn't following the art :P
On another note; As top heavy as it is, heavy legs to support the mechs weight makes sense. It just looks that more bulky due to the way the torso tapers down to the waist.