Well to add to the above...I have owned both types, including the 6922 in one of it's finest outings, the CJ ART, and also the 6H30 in the BAT SE gear.
I think alot that has added to the 6922 warm musical vs. 6H30 dryer, etc...situation is what has been done at Audio Research. My results are in favor of the 6H30, and I feel that, done properly, it is the more musically accurate.
For what it's worth, one of the best modifiers out there, Dan Wright, is now working on mods using this "super tube".