this has come up on every mybb release, but seriously, what essential features are you missing here that are in mybb 1.6?
some 'brand new' features in mybb1.6 according to here
and other custom stuff wdz added from newer mybb versions:
pm search <- check
thread prefixes/video mycode <- meh
undoing votes <- lol? has been a feature on here for years
inline editing <- check, via userscript
shoutbox <- check, way more awesome than the mybb one
reputation system <- check
thread activity indicators <- check
i just don't see the advantages of upgrading the forum for the sake of upgrading..
there have been vague plans of restructuring the forums in the future now that we have yuna and i have nothing against that if it adds real benefits.
(....that is, as long as the shoutbox stays the way it is and dz isn't put out of his job as admin
oh, and: other stuff that we have that isn't in mybb (afaik)
and all its tweaks/config
detailed forum stats
ye olde smiley inserter
quick quote (mybb has something similar-ish though)
reputation deletion log
and probably some other stuff i missed