I've put about 10k miles on my R with the Haldex controller from HPA, and thought I'd post up my thoughts on it so far.
Went with the wireless switchable controller and only take it out of race mode every so often on longer highway trips. Other than that, it stays in race mode all the time. Lost a couple MPGs in fuel economy in race mode, but nothing that bothers me all that much.
One of my concerns was winter driving, this is a non-issue for sure. The car still performs well in race mode in snow/ice, and switching off ESC just increases the fun factor if you have space to play around in.
Can't wait for spring to roll around to put in some track time in the R! Considering swapping to the competition only controller considering how rarely I take it out of race mode.
Have a BNIB blue unit. Wondering the differences and if I should sell and get your stealth upgrade.
The HPA "Comp" unit provides the distinct advantage of not disengaging the rear end under a touch of the brake. There are many circumstances when this will work to your advantage, depending of course on how you drive the car (and if you track the car as well).
The whole purpose of an aftermarket controller would be to have the rear wheels engaged as often as possible, so...
We've been getting a lot of snow lately here in Minnesota. I gotta say that the competition haldex controller is AWESOME!!! I feel like I have total control no matter what. Leaving trucks in the dust is so much fun! Maybe they just don't suspect the mk4 R. Hahaha. Traction control off! And let the rear end hang out. When I want it to straighten out it comes right back, even without getting out of the throttle. Anyways just thought I'd let you know