Money aside the only con I see is the clutch will be limited unless they release different plate thicknesses to allow more plates. A quality 8 plate will hold approx 900-950 ft lbs. The plates they use are not compatible with anything we have right now.
We have built 2 of these so far and the builds went together extremely well.
Great insight into the HKS transmission ugprade. Would this be a concern at all for a car that wouldn't be launched, but would be used on a road course (repeated shifting from between gears 3-4-5)?