That sounds perfect to me.
One thing I want to say is that I hope the first WotLK tier (Naxxramas / Deadly Gladiator season) won't last too long because it's a pretty damn boring part of the progression and it becomes stale pretty quick (At least for me I don't know how others feel about it), I experienced this on another very well scripted x1 3.3.5 progressive server where the Ulduar tier got delayed for so long that half the server got bored and left pretty much.
PvP is also a mess with such low item level gear coupled with 3.3.5 talents and Naxxramas isn't a particular challenging or interesting raid so it's not so great if it lasts too long.
The next tier on the other hand though.... very different story, Ulduar is easily one of the best raids in any expansion and GL to the guilds out there trying to clear Ulduar 25 hard modes if it's scripted properly :p ... it's gonna be tough but very fun and rewarding at the same time.