Just curious why you're not interested in SIDIs again? I've had 2 pair over the years and its the only boot I'll buy - sport or dirt. The soles on my most recent pair (Vertigo Corsas) are really worn from riding my Hypermotard with my foot out in addition to some fast lowsides on the track years ago. Some spots are ground flat like the Ti knuckles on my gloves. Will probably go for the model replacing the Vertigo Corsas when time to replace.
Race boots as in you're racing in them or tracking in them? Daytona boots. Expensive but the absolute best IMO. Don't skimp on protection.
Not a specific reason, just probably because I'm not willing to pay $500 for a pair of boots. I'm considering AXO too since I have leather and gloves.