Addendum:

> compared to the e500mc the e5500 has twice the single precision
> performance per clock and up to quadruple the double precision
> performance per clock.

Nothing about FPU performance, but an interesting comparison between e500mc and e5500 regarding integer related performance:

http://www.power.org/events/POWERWEBINAR082010/PowerOrgWebinarMilAeroGieske-1.pdf (page 13)

According to the rightmost chart the e5500 delivers only about 76% of the DMIPS per Watt delivered by the e500mc.