I bought one of each from TSC (subsoiler & middlebuster) last spring while doing my homesite. I needed to break up some chert rock and tried the subsoiler - it worked great. Like already said, it just barely clears the ground in transit but will dig pretty deep, about 12". It held up to completely stopping my 41 hp tractor when I'd snag a good chunk of rock in low gear. You definitely want to go slow when that baby is down all the way. As far as the middlebuster, I haven't used it yet. As already stated, it won't go as deep as the subsoiler, that is plain to see when they are side by side. Also, if your ground is rocky, I would imagine the plow would get bent fairly easy with a stiff snag. I bought mine originally to use in the garden but a good friend gave me a really nice 3 bottom plow this spring and didn't need the middlebuster. One of these days I'll have a need for it though.