>> T4: 3.3 DMIPS/MHz * 1800 MHz = 5940 DMIPS

> Freescale insists that e6500 delivers 6.0DMIPS/MHz.
> But we agree that it's only when hyperthreading (SMP) is used?

Yes, as this is exactly what Freescale says. In June at FTF, they revealed that a single e6500 thread delivers 3.3 DMIPS/MHz. See there:

https://morph.zone/modules/newbb_plus/viewtopic.php?forum=3&topic_id=7001&start=743

And due to the fact that a thread (or 'virtual core' in Freescale speak) is not a full core it's only logical that a single thread running delivers better than half the performance of both threads running in SMT mode.

> To me it seems that T2080 could be pretty good PA6T replacement.

Yes, from a desktop computing point of view, the only drawback of the T2080 compared to the T4240/T4160 is the lower number of SerDes lanes available (2x8 vs. 2x16/2x12). On the other hand, the T2080 should be way cheaper than the T4 chips. And we should take into account that the bandwidth per SerDes lane of the QorIQ T2/T4 is quadruple that of PA6T's bandwidth per SerDes lane.