In that case, the PPC had probably a 5-10x perf advantage over the 68k's people were upgrading from. So, it wasn't noticeable, so if in the end the emulated code was only running at the speed of the 68k it was replacing it was a net win every time it entered the kernel and ran native code.

ARM doesn't have this advantage over X86, at best its probably somewhere around 1/2 the absolute performance. Of course intel has been selling a _LOT_ of really slow CPU's down the product line, so for someone upgrading from a atom class machine the ARM will probably appear to be pretty reasonable. Not so much, if your running a fairly high end laptop.