The 70 bracket will have a bunch of arena-geared, experienced PvP players bouncing around looking for you in your greens and PvE gear. Especially now that S4 is coming out. You're gonna get killed, a lot. At least at first ;)
I wouldn't say that it's "faster" to grind honor at 69 as much as it's a more even playing field and a bit easier to survive (and learn) a bit longer.
For myself it wasn't about the honor/hour ratio as much as it was about gathering up the different marks as I leveled. Honor gains became the goal at 70.
Good luck and watch out for the rogue!