I only have one 000, and mostly use 0 and 00 for detailing, and, like Steve, I use ProArte. This is mainly because when there are so few hairs on a brush of this size, any sort of firmness is very important to me, only the very best sable can compete, but here we see the law of diminishing returns! This all being said, I don't do ultra-fine detailing like, say, Ralph, and I suspect that this would require top drawer sable. The beauty of Pro Arte to me is that they are very high quality (if, like me, you go through every one in the rack
) at a really affordable price, and if you have a really robust cleaning regime*, they'll go for a long while. I also have a large collection of W&N Cotman brushes, which are pretty decent too. One final tip though (see what I did there?) is that if you have a series 7 W&N sable brush at size 2 or 3, the tip will be of an extra high quality and is therefore very suitable for really fine detailing - requires a different technique, but it works!
*after using a size 00 to paint road tyres on 1/35 tank wheels, I'll spend a minimum of 10 minutes cleaning that brush