ECC88/6dj8 and E88CC/6922 have different maximum current specs with the latter being able to withstand higher levels.
Probably best to ask the designer/manufacturer as to what will "last well/longer" in a specific unit, and if this is not possible then perhaps confer with a reputable tube dealer and/or a forum with knowledgable experts (diyaudio?) who may be able to offer advice.
Think there may be a few exceptions (regarding longevity) like early Telefunken CCA's (a 6dj8 as I understand it), but I may be wrong on this.
In addition there is also the E188CC/7308 that is said to be even more durable (in higher current circuits) than the E88CC/6922, but I'm too lazy to look up the spec's on all the, above mentioned, versions.
In the Audion/Consonance gear I've owned/used I was able to use 6dj8's in place of the specified 6922's without premature failure, but in a friends Audible Illusions preamp I ended up using extremely durable Russian 6n23-EV's and Telefunken 7dj8's (phono section) which lasted for many years (wasted/trashed some old production 6dj8's and 6922's experimenting, but I had gobs on hand @ that time).
Neither of us liked the sound of old production 7308's in the pre, so those were spared the long term test (ended up selling many of them here on A'Gon and on Ebay).
DeKay