No, have never tried the 510s, but have heard about them and considered giving them a try. Just never had any issues with the wide variety of shoes I use on all my flats. Thanks for the warning.

Took the Krampus for a pavement ride, yesterday. Did a total of 25 miles. 4 were gravel/sand, but all the rest pavement. Very comfy ride, kind of like a faster Pugsley. Definitely a capable shoulder riding bike like the Pugs, too. Nice to have as an option should I ever need detour or get off the road, quick.

Only issue was that the Krampus felt so much like the Pugsley that I kept reaching for those Jones Loop bars which weren't there (have them on the Pugs). Definitely need to add the Jones to the Krampus if I plan to do a lot of road work with it.