You should try them out...
I picked up two related fish a few months ago - Pseudohemiodon apithanos - and they have quickly become one of my all time favorite fish. The Pseudohemiodons, like the Planiloricaria, are sand dwelling loracids, they spend all day walking around on their pelvic fins and burrying themselves. My Pseudohemiodons are very social and always hang out together - although they have staged, and very amusing, twirling fights about once a day - I'm hoping they might breed soon. Both the Pseudohemiodons and the Planiloricaria are also pretty easy to feed compared to more conventional Pleco types as they readily take brine shrimp, pellets, and even go after flake if its sitting on the aquarium bottom. Planiloricaria apparently do get larger than most loracids though, a foot at least, not including the whip, and they need some open sand or gravel beds to hang out in.
Bottom line: Sand loricids are very different from anything else out there and definitely worth a try.
-Sam