Like I said, I almost never bid from GUI. But, I also know how to spell pretty much anything I'd bid on from memory, and have a private plugin to query AH history on a single item and show it ingame, so I'm not using XIAH either. Even with that in mind, there are a few things I'd rather use the menus for (dynamis void/shards are a good example: abbreviations make spelling them annoying, you likely want a few different ones at once, and they are all in the same category in a predictable order).
Would like to replace the AH GUI entirely, but hesitant to give out code to query AH because of potential abuse/ddos(it's not tied to the game instance at all and it openly accepts all requests).