Honestly, I would prefer not to switch the thing to pronounced digitigrade locomotion. It would be nice to see a cleaned up and improved version of the canon artwork, rather than a whole new battlemech. (I'll admit that pic #3 looks like it is probably supposed to be digitigrade, but with a much shallower knee angle, kind of like the Thug.)
I see where the odd, two-part structure of the upper leg in B-3's sketch, and in canon image #2 could be interpreted as a digitigrade joint, but there is also a knee-looking joint for normal locomotion right below it.