Upload & Sell: Off
If Elinchrom would make their adapters out of nickel or steel and change the power settings so that the BXRI 500 went down to 9ws this would be a no-brainer.
Or if buff would make a $100 version of the cyber commander that supported 4 groups, and a simple up/down button it would be a no brainer.
Give thought to Profoto for your next lighting migration. Well, okay, that means selling your house and living under a freeway, but we can dream. The new Pro-B4 has energy range of 1-1000Ws which I think is a new record, and should handle most situations. Otherwise, Brian's suggestion of an ND gel in the SB is sound, if slightly inconvenient. Alternatively, apply ND filtering at the lens. Solutions imperfect, solutions unaffordable: take your pick!