This is indeed an interesting topic.
Benchmarks are quite complicated things. What does one actually measure, and does the results make sense to compare with ones run on another architecture?
SysInfos "speed" test, for example, is quite a "stupid" benchmark. It tests very few instructions, and in a very repetitive manner. It makes more sense for testing 000-020 than the more advanced architectures. If we wanted, we could optimise the Natami 050 core to look super good in SysInfo. But this would not necessarily make much sense for achieving good real life performance.
AIBB is a lot more advanced. Maybe we should make an AIBB profile for Natami. I have not used AIBB much myself, though.
However, I think it makes more sense writing "new" benchmark suites for the new classics like FPGAArcade and Natami. There are so many aspects which get lost when running benchmarks made for an A500. Not saying the old ones should not be run too, though

Here is a small benchmark suite written by Rune of the Natami Team. It runs code optimised for 030, 060 and N050 in sequence. Source included.
http://www.4shared.com/file/me92duH4/sp_benchmark_11april_.html