I'm going to say this because I assume that you don't know. But maybe you do so here it goes.
The
sigelei Zmax is made be Sigelei and the original Zmax is made by Smoktech. The Smoktech Zmax is the non-OLED screen and has a screen that is similar to the Provari.
Smoktech came out with the Zmax first, and then came out with a revised one called V2. The difference between the V1 and V2 is that the V2 has the eighth menu screen so you can switch between RMS and Mean. Again...maybe you know all this.
Sigelei took the same internals that Smoktech uses and put in an OLED screen. All the ZMax clones (they should be called clones since Sigelei is just copying another company) that Sigelei makes are the V2 with the eighth menu.
As far as that hole is concerned. My Sigelei Zmax didn't come with one. It a solid center post. So I don't know what the use of that hole was. Airflow? Anyways, I have good airflow and I'm glad that hole isn't there. As a matter of fact that hole kinda concerned me when I bought mine, not knowing if it would have a hole or not. I've had mods break all because of the center post was not stable.
Your last sentence asks about Zmax changes through it's production life. Well thats kind of a work around question. Since the company who makes it is China based, the answer would be yes and no. If you are vendor then you could ask for whatever type of specs you want on your Sigelei Zmax or whatever other ecig you were ordering from China.
Here is a link to the Sigelei company.
ZMAX_SIGELEI Electronic Cigarette -
When Pbusardo mentioned in the video about Sigelei making some changes...that was the change. No More Hole in the center post.
As for standard changes other than that hole. Maybe someone else can chime in.
