My unscientific quick impressions after driving the HP version on Charlotte Motor Speedway's road course vs my non-HP on the street
1) engine power delivery feels the same
2) steering feels the same
3) Magneride smooths road impacts on the street the same
4) suspension firmness is slightly more in HP than non-HP
5) Magneride firms up a bit more in the turns in HP vs non-HP
6) larger wheel and tires provide more confident grip at higher speeds in HP vs non-HP
7) brake feel is the same
Some variables to consider in my assessment...I don't have the same sort of speed levels (50-65mph vs 80-85 mph) in the non-HP suspension action when turning on the street. The tires on the HP cars at the Track Attack are Michelin Pilot Sport All-Season 4S, not Pirelli Trofeo RS, the wheel studs on the Track Attack HP cars are slightly longer, and I am a novice when it comes to being on the road course. At the speeds I drove, they were probably 15-20 mph slower than the instructors when I did the ridealong.
I chose the non-HP because I couldn't justify the expense of the HP larger wheel and tire set for my primary use case. I drive my car more on the streets. That said, if I were to do it again, I'd consider getting the HP and plan for the expense of a separate set of tires (and probably wheels). I like the look of the HP front splitter, rear wing, stance, and bigger wheels and tires.
I assume a more experienced road course driver would give more details and impressions than I can.