Just bring the stock X-pipe to a good exhaust shop and they can cut the secondary cats out for around $200 at most shops. They can always weld them back in if you want.
The Fabspeed is suppose to avoid the Check engine light most of the time and if you add a tune, you can turn off the O2 sensors. Main advantage is you don't have to cut the stock X-pipe.
Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."