Since they changed MP cost, I now maintain equal amounts of of vit/mnd/pie

Here is why:

Vit is obvious with HP/def

Mnd managed MP pool and Healing (I also use conj in conjuntion with THM (50 thm, and just hit 39 on CON)

Pie Reduces chances of your magic attacks being resisted (spell accuracy) and Increases your chance of resisting magic attacks of others, as well as modifies DoTs.....DoTs are the most damage to MP used in the game

I find equal value in all 3, thus I added points to them equally.

And to answer your question about leveling con/thm equally or not, I say not. I got both to 20 them focused on thm (planned to have my thm as main also). Then I went back nd leveled on my conj in between raiding NMs and leveling my craft.