They are good. Part of this depends on how big a spot you are trying to touch up. The tips on these eyelash doohickeys are very small, which are good for small chips, if you had one 1/4" it's not going to be so good.
I find the most important thing about touch-up is the thinning of the paint. It's too thick as it comes out of the bottle, you really need to thin it. Of course this depends on the technique you are using. I have tried all of them, I think. You can put a big blob on there, and smooth it using the Langka/Dr. Colorchip technique (or use an old credit card, some thinner, and an old t-shirt). Or you can tape off and wet sand the blob down and blend it. Or you can thin your touchup and fill the chip with several layers of very thin paint. If you do this very carefully, you will leave yourself enough room for some clear on top (maybe).
Back to your question, I think the little micro applicators are something you should have on hand if you can get them cheap, or are ordering from Eastwood or Griot's. (It just occurred to me they might have these in local stores like Harmon's etc., I actually started looking on Amazon thinking I would find them in an automotive context). But I also have some small brushes like you have that I bought on sale in an art store chain that was closing. Just like detailing you need to have several methods/products on hand to match to the problem.
