An option to consider: When they would hit 7th, give a feat, as for E6. When they'd get the second bonus feat, they hit 7th. Then 2 or 3 feats before hitting 8th. Then, they never reach ninth.I can see that point.
7th and 8th level characters should be akin to Hercules, Jason, King Arthur, Merlin and the like. Legends among men.
I'm still highly debating the merits of both E6 and E8 and have not made a decision.
E6 is certainly more in the realms of human while E8 reaches the beginnings of superhuman.
But E8 really does seem to work better as a break point for Pathfinder classes.