I'm impressed, they feel pretty good. Slightly firmer than stock but it's more of a controlled firmness, not a "I've got 2X4's under my leaf springs" kind of firm. I like them enough that I'm pretty sure I will be getting the matching shocks for the back now as well.
I looked at the 5100's as well but decided on these after reading some reviews on other Truck and SUV forums that the Eibachs have been a more popular application on, such as the Tundra, Tacoma, and 4runner.