I just got an AK2, so I can't vouch for any stability improvements, but I'm discovering that the newest version has its own stability problems.
Does everyone have problems with DSOrganize or is it just me? Sometimes it loads fine, but usually it doesn't (it gets "stuck" on the loading page, running the loading animation for DSOrganize, but never completing the load).
I've also noticed spurious white/black screens with various games.
I used a DSTT before getting the AK2, and it never seemed to have these kinds of problems. I like the menu system, so I sure hope they'll fix this stuff quickly in firmware releases because this is the type of thing gives an otherwise great cart a poor first impression.
-Bri