Daytona, Sebring (long), VIR, Homestead, Road Atlanta likely no problem.
Sebring (short), Roebling, Moroso and others where cornering speed is crucial, it will give other drivers fits.
Having driven both IT and AS, I can tell you that the cars are worlds apart in the way they are driven. And it appears that the AS cars (Mustangs, specifically) have gotten fatter since I ran mine, which exascerbates the problem.
I don't think there is a problem from a safety stand point. I simply hope that there is ample give and take on the track. AS and T1 are used to getting passed by the faster GT cars; I hope that ego doesn't take over when getting passed by an ITS car or ITA Miata. Straightaways are no contest, but it will put a higher premium on late-braking and watching mirrors on corner entry.
I can live with it.