Phase-II makes *both* styles. I know, because I opted for the wedge style when I got mine
The dovetail, you mean?
And I have seen one old Aloris one in the piston style.
I agree that the wedge style is more rigid (which is why I got that to start with, even though it cost a little more from Phase-II.
The Dorian toolpost is sort of a cross between the piston and the wedge style. It has a small piece which projects out of the outside dovetail -- or the one towards the tailstock for the boring/facing station) which in effect does the same thing that the wedge style does. And the lever does *not* swing in a full circle, unlike the norma piston style. (See Below for significance.)
Agreed there.
Another consideration between the piston and the wedge style is that (with no tool holder on the post) the piston style's locking lever can freely rotate a full 360 degrees. This can bring it into the path of the chuck jaws, and result in Shrapnel as the plastic end of the handle shatters.
I did not know about this "feature" until I had already gotten my Phase-II. It made me even more glad about my choice.
Enjoy, DoN.