I don't use a Summit, but have witnessed some disgustingly good putting from brotherdave several times with his. I'm sure practice and technique help, but it can't be all bad and make some of the shots I've seen him sink.
Discover new ways to elevate your game with the updated DGCourseReview app!
It's entirely free and enhanced with features shaped by user feedback to ensure your best experience on the course. (App Store or Google Play)
Summit and Pure:
Spush putter here. I use a Summit as a long putter currently (> 45ft) paired with a Zero Pure (inside 45'). Both fly the same within the circle, but the Pure has some fade at the end of it's flight, whereas my Summit goes straight until it hits the ground. Like a beat in Pure that will just hold the sweet spot...