Headaches
I understand and sympathise with your concerns. They are valid. After all, what's the point of having a powerful card counting if you're going to make errors.
Can I suggest that unless you're prepared to really work at it, I'd stick with KO. You can get around the headaches with using AOII, but it takes a lot of time and hard work. I think it's worth it, but my friends wouldn't think so.
Do you know all the indices yet? This is how I learnt AOII.
I divided each line into Player vs Dealer 2 to 6 and Player vs Dealer 7 to A to create "strings" of indices to memorise. This way, I would be able to recollect the strings of indices without error, and later associate individual plays with individual indices.
An example:
12 v 2 - Stand 5, 2, 0, -2, -2 (which represents v 2, 3, 4, 5,6)
12 v 7 - Hit (which represents 7, 8, 9, 10 A)
I would then rehearse them like times tables.
Until they are thoroughly learned you should use basic strategy. You will find that you will be using basic strategy most of the time anyway, even after you have learned AOII thoroughly.
Now true count conversion: That's another story. For me, the best way I've found is to learn what the true count equivalent is for each running count number per half deck or quarter deck. This is a lot of work but it means that there is less calculating to do on the spot and therefore less pressure during play.
In order to play well, you need to have downtime during your play. If you don't you will be "full on" all the time and you will crack when the pressure gets too great. The way to do is to play basic strategy on all negative counts (unless the indices are easily recalled) because this is when you're less likely to win anyway and you will theoretically have minimum bets out. This will give you breathing space and time to gather your composure for the big counts when they come.
The beauty of AOII is that it gives you a clear idea of when you have the betting advantage (especially if you side count aces - goes from .92 to .99 efficiency). With KO you're flying a little blind, because I think any advantage is understated early to mid deal and overstated near the shuffle. I think this is the nature of unbalanced systems.
The other advantage with AOII is that, with so many indices, you get a pretty clear idea how close you are to varying your strategy. This, for me, creates confidence in playing (and in varying from basic strategy when required.) This is like a big picture view of the game in progress.
I hope this helps. Feel free to ask more specific questions if you wish, or email directly.
Alan