I've put about 6k miles on my RE pulleys. A buddy of mine having troubles about the belt slipping/breaking but mine is working fine thus far.
Weird how you feel the difference above 5.5k, I think the exact opposite. I find it VERY noticeable under 3-4k in how much faster the car picks up. It's 8whp/8wtq throughout the whole power band, so 8wtq is very noticeable/useful under 3k. Also my milage improved a solid 1+ mpg average per tank. Well worth the $ but warranty issues does scare me a bit. If I were u I'd go dinan just because of the warranty and they claim it's the most aggressive pulley. RE is on the conservative side I think. Up to you but I've been happy with my RE pulleys