IMO, pure int is not a loss in damage output. I can bring some stats to show you in custom vs enchanted (level 55):

Both of these were on a level 56 pure int mage with the same ring, before the facial bonuses took effect:

120 Dex; Rest Int; Custom Recurve Set
Min Max
Heal 106 214
Ice Storm 181 209
Frostbite 221 265
Fire Blast 274 360
Lightning 267 368
Drain Life 304 415
Main Weapon 206 251


Enchanted Gemstone Staff (Pure Int); 72% chance of Crit Buffed
Min Max
Heal 132 269
Ice Storm 209 245
Frostbite 259 316
Fire Blast 325 438
Lightning 312 442
Drain Life 355 498
Main Weapon 231 269



If you were to take the average, you would find that pure int has higher overall damage, especially once armor is taken into account.