I've been using the Stilo ST4F Composite since July and absolutely love it. As others have mentioned, the add-ons are great and are what sold me on Stilo. So far have mostly appreciated the noise attenuating earmuffs as my race car is loud. I added the integrated radio option and will be picking up radios this winter. I will say it took me a bit to get used to having a mic so close in. I'll also be adding the air supply system for hot weather driving. And seeing as I just finished my first enduro this past weekend (and loved it!), I'll also be adding hydration.
Just a girl and her 837 ponies...
2013 Santorini M3
2012 A4 Avant (winter beater)
199x Sapphire M3 (because racecar)