There could be perhaps some minor improvements from moving around the punctuation keys, but even if it will improve one aspect, it might make another aspect worse. Overall I estimate that the layout is pretty close to the theoretical maximums. Moreover, most of the other layouts have at least one glaring flaw, and I believe that Colemak balances everything rather evenly. The V and B would be better switched, but they're left for compatibility reasons.

The W moved [in the old Colemak version] because it was almost the only letter that doesn't cause a high same-finger ratio with C and R, and it fits well from a finger balance point of view.

Why did you move the W back then between the two colemaks versions? I'm just curious

There are two arguments:
1. Less frequent keys take longer to learn, because it's harder to find a need to use these keys.
2. A more common key requires to more commonly relearn letters, causing frustration. First argument isn't true because there are typing lessons for rare and common letters.

My experience with moving different keys a few keys at a time has been that the less frequent keys cause the most total frustration. The frustration of the common keys is quickly overcome – especially since these almost always move to better positions (or they wouldn't be worth moving). The flow disruption caused by a mistake lingers on for the less frequent keys for a much longer while after moving them.

Again, your claims seem poorly thought out, Piotr. I think the first argument is very much true based on experience. And the lessons for rare letters are boring, frustrating in themselves and don't really help that much in my experience. I'd rather move a few keys at a time like Tarmak does and keep typing interesting stuff!

Most of the 'typing lessons' don't teach typing. They require you to repeat e.g. "gggg jjjj" "gjgj gjgj" to learn where the key is placed, but that doesn't help with normal writing.
There is more info about that on keybr's help page.