Did you both realised that TBC is not retail ? Iam sure its ovious right ?
So there are reasons for that, makes sense too right?
The cashshop is one big reason. If you want the boost, even its makes for you both on a personal lvl, it will lead to tbc changes to retail in some time. So ultimately you could actually just play retail instead, because it is only a matter of time then, until that change will happen. (This is not to be ment to be offensive)
So what do you want? TBC as a botinfested and economybroken cripple that is limping in the direction of retail or you have to lvl yourself ( 15% les xp needed + new questhubs) and keep that what makes tbc what is was. You cant have both.