A few random comments: Both the long handle BB and short handle weight the same (69 g) Almost the same as a Slim (70 g). The balance point measured from the base of the head is the same for all three, however the Slim knurled adjuster is positioned slightly higher on the handle which may give the perception of a lower grip and a better balanced razor. As has been mentioned the BB with the nylon adjuster plate (not base plate) is significantly lighter (58G) I find this to be the best balanced of all versions. (Also the nylon version loooks beeter in real life compared to photos) When set to the same blade gap (which might actually be a different numerical setting), I find the shaves virtually identical for all BB's and the Slim.
For those who have commented on reduced blade life and/or reduced comfort compared to a Fat Boy this may be due to the shaving angle. Due to the less rounded head , if the same handle angle is habitually maintained as used with a Fat Boy, a slim or BB will provide a steeper blade angle compared to a Fat Boy. Steeper angle = more blade friction, hence less smooth shave and decreased blade life. Lifting the handle might improve the shave. As I don't own a Fat Boy this is speculation that while correct in theory may prove wrong in practice.
For those who have commented on reduced blade life and/or reduced comfort compared to a Fat Boy this may be due to the shaving angle. Due to the less rounded head , if the same handle angle is habitually maintained as used with a Fat Boy, a slim or BB will provide a steeper blade angle compared to a Fat Boy. Steeper angle = more blade friction, hence less smooth shave and decreased blade life. Lifting the handle might improve the shave. As I don't own a Fat Boy this is speculation that while correct in theory may prove wrong in practice.