I do that sort of thing a lot with bikes. One year I needed brakes and bought a set of those Rever mechanical ones just because they were new that year and I was curious about them. The same with flat fenders, actually. I needed a set of fenders, and had never tried flat ones. Most recently I tried a set of WTB Padloc grips just for the fun of it. If you have disk brakes and enough clearance, you could go 650b on the second wheelset and play around with the road-plus tire sizing.