I had not heard of jackbrake before this thread and not noticed it on the prophet or the morewood. So its not an issue for me.
However I have changed all the bearing on a giant glory after 3 years of light use (Fuk doing that again).
Never needed to changed the one on my prophet after 5 year, still feel solid.
In my opinion Single pivots are fun to ride and simple to maintain.
I will never buy a bike with as many bearing as the glory again. For me its more hassle than it worth in the long run.
Might consider a single pivot + linkage but not this time round.