Interested why you switched from 9x9 at 2 stones. I've been playing SmartGo recently (iOS) and figured I shouldn't switch to a 19x19 board until I could give it a good game without a handicap, but have stalled at 2 stones. My logic was if I can't play the 'right' moves at this stage, what hope do I have on a larger board?
The problem with the 9x9 board is that it is just too small to allow you to really play go, it turns into a different kind of game. I think it is better to switch to a bigger board. It doesn't have to be the complete board, you can have some intermediate steps. The 9x9 board can be used to teach the absolute basics, but don't stay on it too long, you are probably not training yourself the right way. If your goal is to beat the computer on a 9x9 that's fine, but at some point it doesn't help you in playing the real game. My feeling is that point is reached real fast.
This is definitely true — 9×9 is too small for a real game. But 13×13 is a much better compromise and I would recommend that to players who have outgrown the 9×9 but still don't need to sit through a two-hour game before they learn from each mistake.
(To be precise, the problem with 9×9 is that often after just a few moves the board is divided into a white half and a black half, and the rest of the game is a yose to decide whose half is larger. I'm sure someone can counterargue that if played expertly, 9×9 is a fascinating and highly skilled game; but in general it's going to lack a lot of the situations you can encounter in a full game of Go.)
It's useful to start out on a 9x9 board when you're still wrapping your head around how to figure out if a group is alive or dead and the most efficient ways to make life in the corner, etc. But being good on a 9x9 doesn't actually teach you a lot about how to play on a 19x19, because there's just not enough space to really have an opening and mid game develop.
Learning how to give the computer a challenge on an even game on 9x9 won't make you better at 19x19; if you understand the rules, the very basic fundamentals of good shape, and you know how to fight in the corner, you've pretty much exhausted the usefulness of 9x9 and should move on.
I switched just because 19x19 is classic, and I heard that that was about the cutoff point where I could be competitive on 19x19 with a 9-stone handicap. Although this is against gnugo - I think SmartGo is significantly stronger and I don't know how its 19x19 play compares.
I know that when I play SmartGo iOS in its adaptive mode, it doesn't even let me try 13x13, it's not unlocked yet. :)
I've just started playing 11x11 vs SmartGo. Indeed I need to work my way up the ranks to get to the 13x13 board. I'm in no rush so it's all good practise!
