No, it’s pretty much a repackaged B5c. So as far as physical component performance there will be little difference.
That said, you will see a marked performance improvement as far as signal loss (no cabling), noise (all metal construction) and signal efficiency (wave guide antennas have proven to be extremely efficient and minimize signal losses to side lobes)
So, in conclusion, in a perfect world, no there isn’t really a difference between the B5x and the B5c (besides fewer antenna options), but in the real world a few dB in losses here and there add up pretty quickly and can make or break a link. Also the B5x packaging is way smaller so it would be easier to fit into some tight deployments.
Rumor mill has it that 6x announcements will be happening at Wispapalooza in Vegas, but I have not heard that from Mimosa people so take that for what it is.