You may've heard that they switched to a different Falken, but it isn't the GRB. Shawn was using the FK451 (shaved) at the first autox of the year. You already noticed where he finished, right?
I'm going to be on Azeni unless the Hankook tires turn out to be a second faster or something (I really doubt they could & still be legal). Was going to keep using the Pirelli PZero Neroes & jump to 225/50/16, but they appear to be discontinued.
I don't really think the difference between the "max performance" tires is big enough to worry about, though (locally). I've tried Kumhos, Falkens & Pirellis, and they're all pretty fast. Only difference I've felt is the squishy sidewall of the Kumho MX. Unless you're out to win a national championship, just get the size & price that fit your needs.