I have only heard bad things about the Art carr trannies, ever since the whole DR debacle.
I dont want this site to turn into a witch hunt either, but from what I've heard/read, Art Carr is building a tranny that has more problems than a stock unit.
Just buy a 98+ tranny, JMOD it, do a force lube mod to the tail shaft, put a shorter reverse servo, and a larger OD band, and be done with it.
Go with a JMOD' 99+ main control, and even better, if you can find a 2001 5.4 liter 4R70W tranny, it will already essentially have bullet-proof gearsets.
You can then add the gears, and the stall you want, and have peace of mind. For the price Art Carr charges for one of their street/strip trannies, you could have one built that can handle alot more torque, and last alot longer, and still have enough money for gears, and a MMX shaft.