I never liked gear swapping myself (except Bard instruments, even though it made me carry around 10 different flutes and clarinets).
On topic, 7 slots is far too few, and it may have hurt the economy. Think of it like this: you want to make Bags of Popoto Chips. Popoto Chips require 2 Popotoes and 1 Jug of Oil to produce one bag of chips. The guy you got the Popotoes from only has 7 AH slots, but has 20 stacks of Popotoes. He wants to sell all his Popotoes, which are easy to get, but can only sell 7 stacks. Something that would be common has just become more rare because he's not allowed to sell his abundance of Popotoes all at once. Since it's been made artificially less abundant, he sells them at a higher price than he could get if the market had more Popotos in it. You now have to buy them at an inflated price.
When you make Popoto Chips, you end up with half as many bags of chips as the number of Popotoes you bought. Let's say you bought 14 stacks of Popotoes, in total, meaning you made 7 stacks of chips. You have enough slots to sell them all. The Popotoes you used were artificially made more expensive, but your chips were less so, because there are already fewer of them as a natural result of them requiring many materials. If the Popotoes are more expensive than they should be, but your finished product is not, you are making less money as a direct result of the low amount of AH slots. The finished product is also made more expensive because of materials costs. Mind you I could be completely wrong, but it's something to think about. In a player-run economy, the fewer snags the better.
Unlimited slots would be best, but 20 or so would be okay.