Eric,

I could see where reducing UPWIND sail area and replacing it with DOWNWIND sail area could indeed slow the overall rating down.

Think of it this way... you're spending a LOT more time upwind sailing than downwind sailing on a typical W/L course, even if the distance is identical.

So, slowing a boat down even further upwind (by removing jib) will drastically penalize your overall "Time to finish" even if you speed up your downwind leg.

I don't have any specific math to back this up, but anecdotal evidence supports my general hypothesis...