Gunnar seems to have already done the comparison at IBM:
http://www.apollo-core.com/index.htm?page=performance"IBM compared three FPGA cores: The POWERPC 440, NIOS and APOLLO. The study was conducted in simulation and on a PLDA FPGA PCIe card using a ALTERA Stratix4 230C2."
I think those are the same results he had 2 years ago before he started adding all the new performance enhancements to the apollo core
