Dont use the +20 vit stones (pure got stones)till you get the Dragon/r8 gear..untill then, the Gaia 300 hp gives the same amount as those pure god stones

If you add just +HP stones then no room for Def ones,
and with less Def you just lose HP faster.
I was using Pdef stones on 4 and Mdef on 2 gear pieces
and it worked better (for my cleric). Slower loss of HP
gives more time to charm to tick.
Now I use +15 Vit from bottom row. Vit gives some def
AND some HP.
And of course +20 Vit for Dragon.