I did full testing of accuracy quite a while ago as i hadn't seen any confirmations. There was speculation only at the time. My full testing showed you need +10% to not miss with Full Auto and High Impact Bolt. I did test at +9.5% in case you're wondering. Test all you want. But if you get a different number then you haven't done enough testing and you would be wrong.
To the OP. Accuracy to +10% is on average the best way to gear. Simcraft shows this and so do my parses.
Depending on the fight the commandos using +10% accuracy should be at the top of the charts. If they aren't then they really need to l2p.
The only question about accuracy is with Ilevel63 gear and wether we should gear to +10.27% or drop to +8.68%. With Ilevel61 gear we hit +9.89% which was optimal. Personally i'm currently at this stage of Ilevel63 gearing and i'm going with +8.68% accuracy as i believe it's more beneficial than exceeding +10% by .27%. A Merc would benefit more by going with +10.27% as exceeding 10% would benefit their Unload offhand. Simcraft confirms this as well. Since simcraft doesn't work with commandos i can only speculate that dropping to +8.68% is best. So i won't confirm that it really is best for commandos. I think it's so close you could go either way and not notice a difference.
Thanks for the tests. This is my thinking as well.