I probably should've done this before, and i have no clue why i didnt, but this is very clear:
Gem: with 80 int + 160 spi
Gem: +160 int
Reforge: Spi -> 155 mst
+ what i would gain from wearing regail over kritak.
- what i would lose from wearing regail over kritak.
So basicly, i would only gain 0,92% mastery and 57 stamina from wearing Regail instead of Kritak