> G3 level Efika

It's G2 level even:

https://morph.zone/modules/newbb_plus/viewtopic.php?forum=11&topic_id=11137&start=744

> a Mediator equipped Amiga with a 500 MHz Sonnet card might be faster than the Efika.

A 500 MHz G3 trumps a 400 MHz G2, yes.

> The fact that a 1.33 GHz accelerator could be built is mildly interesting

Why would it be restricted to 1.33 GHz?

> isn't the TeronOne almost the same as a Pegasos I?

Yes, the latter is based on the former, with some enhancements like newer southbridge.

> the only reason the X1000 has never gotten any love is because of Ben Hermans' involvement

For some years, and as Hermans left A-Eon prior to the X1000 release, the fact that the PA6T and thus the X1000 are no longer and won't ever be available new might have been the primary reason.