There are so many versions of the V2 (and now V3?) pens that it's really unpredictable.
They have different number of ridges on the selector, better and worse printing on the selector dial, square vs rounded edges on the push button, some with labels showing units on the cart holder, others without. Some of these are better and worse for reliability and smoothness, but often the pictures of what is being sold don't exactly match what is delivered, which makes distinguishing them a crapshoot anyway. I own 5 different pairs of V2 and they appear to be 5 different pens. For $15-20 ea I want recommend splurging for a something better, but they come in such pretty colors!
At the same time, all of them have worked OK and only one was repeatably off by a unit. One of them was a bit sticky and some teflon spray fixed it. YMMV!
My once beloved Bird Pens appear to be no more. It's Gensu2 or bust.