The biggest thing you'll miss out on in the IC is the blind spot camera views, really. The rest of the stuff in the 7" IC I can take or leave- the sport tab post-refresh really leaves a lot to be desired; the gauges are too small to be useful when needed, the lap time and g-meter are gone, and the nav hinting is duplicated in the HUD. It looks nicer, but unless you want the additional functionality like the blind-spot cameras, I wouldn't make the GT2 vs. GT1 decision based on the IC.
Other than the blind spot camera, I'd argue the refreshed model's IC was a downgrade.