I don't want to be a debbie downer but don't expect Honda reliability. There are numerous possible issues when you purchase a new mustang from the MT82 noise/shifting problems, front lower control arms creaking, paint issues (hood paint bubbling and other various problems), engine tick, etc. In 13 months of ownership I've encountered all these issues except my MT82 has been decent so if you go into it thinking it won't happen to you you will likely be disappointed.
That said there is a lot to like about these cars outside of some of the issues. The car feels solid and is fun to cruise around with especially if you have one with the Brembo package. Fuel mileage sucks period regardless of how you drive but that's the price for 400+ horsepower.
I would drive a Brembo equipped car and a regular GT back to back to see what you prefer. There's a big difference and coming from an RSX you may not like the floaty ride that comes with the regular GT suspension.
Interesting. I was prepared for slightly lower reliablity, but didn't really think there would be such a long list of issues