Lag aside, am I one of the few people who actually liked the tax being in the AH? It provided a reliable way to pull money out of the economy and keep some sort of control on it, however imaginative said control may have been.
Now, those with better connections can set up a shop and just leave for a while, allowing their items to sell while they're afk and not pay any taxes on it. Those with worse connections still have to use the AH.
This strikes me as a bad idea all around. Prices won't really come down much, and are actually going to be harder to know as all the people who have the high cost items start PSing them in a spread out area. People with bad connections are going to feel slightly punished for the above reason, as well as joining the ranks of those with poor/no graphics cards in the case of the oft mentioned lag increase.
Can this be an experimental feature before it's determined to be a finalized full feature, please?