You are probably correct for about half of what you said lol. For about Half of this expansion we will have to stick with 2 pc T8. As graylo has posted on his boomkin blog having 4 pc T9 is about a 6.94% dps increase where staying with 2 piece T8 and 2 piece T9 is about a 6.14% increase in damage as apposed to no tier gear. Now granted you would have to have 4 piece of the 258 ilvl, I think that will be attainable after the raid tonight and seeing some of the content.
1 wipe 1 kill :P no ptr xp for any of us