Just started using my pair, and I find that I like them with the shim, giving me a very snug, tight fit. (I like my skates to be very snug in general - I wear skates 2.5 sizes smaller than my shoes). I started using them with Stable 26 socks, and now I have very little negative space in my boot, which is great. Not sure if there's a significant performance difference from using the Powerfoot inserts (and the Stable 26 as well), but I'll tell you this... from a comfort standpoint...it's fantastic. It's also prevented me from curling my toes when in stationary positions, which has caused aches in the past. And for less than $20, it's a great value. I'm sold and am already recommending to fellow players who have complained in the past about roomy toe boxes.