Button locks are very smooth and anything from Brian will be of great quality. However, keep in mind that as many openings start to slightly deform the stop pin you can start to get button creep and stick on a button lock. If Brian's done something to mitigate this, I haven't heard of it.
Smoothness comes from a lot of factors, such as lockbar tension, blade finish, and tolerances. A knife with a weak lock bar tension (thus less force on the tang by the detent) and lapped washers will make a knife feel smoother, for example, and you can easily make many well-made folders costing relatively little extremely smooth by easing this tension and polishing the washers. So smooth that they might rival an expensive un modified folder in smoothness.
Keep in mind also that the same model of production knife will have variances in smoothness between knives since so many factors go into making a knife smooth, and because these are mass produced pieces. You might get a Strider that's smoother than a Hinderer, for example, or a Hinderer that's smoother than a Chris Reeve, but that doesn't necessarily say anything concrete about which brand or which model of knife is smoother than another.