Ok, thanks Miothan & Salan, that were the answers I was looking for. So atm I can stop investing in Dex and moreover I can switch to armor with other stats than Dex to improve strength or vitality as long as Dex is not lowered below 500.
Do the other stats also have a cap?
STR: Each point in STR increases damage done with %weapon DPS abilities and physical damage abilities, however, at 1,000 STR you stop getting any +crit damage from STR as the cap for +crit damage from STR is +400%.(+0.4% crit dmg per point)
DEX: 500 Dex is the cap, you gain nothing after 500. (dont remember the exact stat gains to dodge and Crit chance)
FOC: Each point in FOC increases damage done with %weapon DPs abilities and magic/elemental damage abilities, at 1,000 FOC you stop getting mana from FOC, but you still increase your magic damage. (You also get +60% chance to execute from FOC at 500 i think it is.)
VIT: Caps out at 1,000, after that you get nothing, not even HP. +block from vit caps at 500 already i think it is, however, VIT has an upscaling curve, so the more you have, the more each point is worth, total gains from 1,000 VIT is 19998 HP. You also get +0.55% all armor per point in VIT which caps out at +550% to all armor at 1,000 VIT which is nice for VIT heavy character builds.
Would not recommend going above 300 DEX tho as the diminishing return for dex kicks in quite heavily after ~180 dex. Better to get STR/FOC/VIT with those points then.