I rode the 5.0" one, it's seriously awesome. You can feel that you actually have something under your feet, rather than a four-inch stick. And it had no noise what so ever.
Comparing TSI to jdbugs or razors or whatever is pointless. Even if a jdbug/razor has reinforcements, you can still break the folding mechanism off several times before something happens to the TSI. That's why i had to get myself a TSI because i kept breaking reinforced pro-models at the folding mechanism (like i did in
this video), but TSI... wow just wow. So solid. And the headtube angle is so good that i could make my bars 3 inches wider without losing barspins.