I'm sorry but I have disagree. You don't have to test every single item, that's just a specious argument. You certainly do have to test class changes especially given that new abilities are added, modifiers changed, etc. However, those are known quantities for the most part. It's mathematical formulas where you're adjusting modifiers, proc chances, etc. Historical release notes exist for both original and classic versions to provide the precise modifier values that I'm referring to. I'm not trying to discount that this project doesn't take real work because clearly it does.
I would say with a certainty that it's not building the server from the ground up. The BC dungeons, NPCs, quests, resource spawns, recipes, world mobs, raids, PvP content, etc. are already in their existing code. For raid content, you're modifying the health, damage, resists, mitigation of the trash and bosses - you're not re-writing this stuff from scratch.
Also, what you're saying still doesn't address my overarching point. Let's assume what you said is true, that they fell behind over the past 15 months - then why post 2 months ago that you're bumping the XP rate in anticipation of the launch of TBC? Why publish a PTR 6 weeks ago if you're so far behind that many things aren't working? More to the point, why would you not just explain to the player base and let them know there is going to be a period between the final phase of Vanilla and the launch of TBC where the XP is going to be increased and maybe items in the shop for this realm will be reduced in price, or double honor points are awarded in BGs for people that love fighting over a bridge in AV. Anything other than basically silence leaving people to speculate because that's what people will do in the absence of information.
Why not release pre-patch, or at least announce it? The quests or zones for Draenai and Blood Elves already coded and do not fundamentally change from TBC to WotLK. At worst, players identify that some talents aren't working as they should and the staff can then verify and fix them - basically forced PTR which will find bugs far faster than on PTR. Pre-patch allows you to roll out the class changes and new races without ever affecting the Outland zone, dungeons, raid content there, level cap increases, new armor, weapons, etc. If you're trying to find issues and make the players happy, let the play with TBC changes on their characters and find the issues. Also I guarantee a large percentage of players are dying to level their faction's new class. Just my 2 cents.
Appreciate the response. Cheers