How does the sound of the PCC88 and PCC189 compare to the 6922/6DJ8 and its iterations?

This is a good source of info: https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html

Alas, Joe has nothing to say about the tubes I'm inquiring about.

Sorry about that ! Brent Jesse Tubes lists and mentions them in the descriptions of tubes.  

FYI, I'm familiar with the readily available commentary, instead I'm interested in personal experience and comparisons.

The sound of a tube cannot be considered without context: it is dependent upon how it is employed in a circuit. One designer using the 7DJ8 to good effect is Tim De Paravicini, in his Ear-Yoshino 868 and 912 pre-amps.