I will be purchasing AK2 soon so I have the same question as yours.
But what I learned from here, through browsing, is that you will have no problems with the official firmware. AKAIO has only added features. I noticed that the AKAIO firmware is late in firmware but they fixes the game issues and bugs pretty well. It's your choice, though. For now, I will be using the official firmware as Im not familiar with AKAIO. I will conduct more research about it (bugs, game fixes). Though, I know it's safe to use the AKAIO. everyone, i think, are onto akaio. just my opinion
regards,
Chris