I currently have a True Blood for spares and toast, and I like it a lot, and so far, no cracking. Before that I had a Belmo spare ball, and a Spare Tire, and they both cracked around the thumb and fingers, mainly because I track fairly high on my normal equipment, and even higher on the spare balls(I hear them thump on occasion).
Tracking over a hole is a great way to form cracks.
drillbit