Just wanted to throw some info in here now that I've finally got my EVODs rebuilt the way I like them and working on my Protank 2, now.
Yes, the EVOD heads fit in the Protank 2. Yes, it'll make for a tighter draw (nice). In fact, my draw tightened up so much that I'm getting almost NO draw now (using it on Vision Spinners, and an Innokin iTaste 3.0). It took a little bit of close examination (I don't have any calipers, though) before I found out what the problem was.
While the two heads are VERY similar there are more differences than just the center post (more open on the PT and less open on the EVOD head aside form the obvious length difference).
The rubber grommet and the metal endcap (that holds the grommet in) are narrower on the protank version allowing more airflow from inside the 510 connector. If I want a tighter draw on the PT it is definitely better to switch out the center post with one from an EVOD.
However, if you use an entire EVOD head directly in the PT, a lot of issues start. Well, they do for me anyway.
The draw is so tight that sucking through the tip basically sucks more juice (and less outside air) over the wick which will eventually cause it to leak, gurgle, and eventually flood before an entire tank has even been used. This was all fixed when I used a rebuilt PT head and an EVOD center post.
I don't expect the Protank 2 mini to have this same problem since the ego-threaded adapter probably (crossing fingers) has a lot of open space inside its base (similar to the EVODs).
This is just making the wait for my pre-ordered Protank 2 minis even more excruciating...