Not much of an argument in my opinion, I would love to have either of these trans!
If I remember the numbers correctly Jamie currently rates his trans at 650 ft lbs and based on his testing to date feels he can safely up it another 100 in the future.

T56 pros: Coolness, shift quality, gear selection for any situation, probably better racing setup for more serious guys, stronger/lighter?
T56 cons: Fair amount of fab & welding required, total cost in 6K range, parts have to be sourced from many vendors and made to play together.
Worth it? yes

Passion pros: direct bolt in utilizing existing components, no fab/welding, less expensive by $1500 or so IF you have 18 spline set up, if not then need new clutch/pressure plate
Passion cons: currently limited availability, unproven in the hands of the Destructive Test Division (public) who can f up a peanut butter sandwich in short order.

I think they both appeal to large, but differing, segments of the hobby and will fill their nitches very well.