My understanding from the various comparisons I've watched is the ITS seats aren't nearly as bolstered as the CTR seats. They're not bad, but they're intended to be more for street driving than tracking.
That being said, I get the feeling you can still use them for track days without much issue. You might need to brace yourself a bit more through the corners, but not excessively so.
No personal direct experience with the ITS... Yet.