I completely agree. That's basically what Microsoft does with hacked 360's. Though, I think a dynamic system would be better. IE, instead of banning the MAC from the network forever like Microsoft does, have the PSN login process do a checksum on the kernel or something, and if it detects any changes, don't allow a login. This would allow people to, say, dual-boot their PS3 (or whatever you would call the equivalent with two different firmwares) and get the best of both worlds or re-image their PS3 to a stock firmware and sell it.