I actually like the Cubitron a bit better vs. the Xtract. The Xtract is sensitive to having a clean back and sander pad to get a grip and not go flying off, The Cube has that thin stiff plastic core which can really saw into anything that it touches (even fingers).
I've only bought the sampler packs because at the time (2 years?) they were the cheapest/disc.
Any future purchases will probably be the Cubitron for Moi.