On the A/C front. I had this in my 3.7 Roadster. In truth, it's not very effective. Yes it pumps out cooler air (even when the knob inside the engine bay on the A/C unit is turned on full) but in my opinion not worth considering unless you are living where it's hot - so not Germany, or the UK - though today could be good!
On the Plus 8 (Aero) it's completely different. Works very well. Nice cold air pumped. Don't use the A/C that much, but when I do I'm glad it's fitted.
Completely agree on headed seats. Had them on the 3.7, and the Speedster. Really good. Two setting: hot and very hot. Well worth it. Use them a lot for night blats.