I main SMN in coil. I can tell you crit is way better. Pets don't work off det, it works of your book. You can take off all your gear and have your 110 weapon on and pet would be hitting same, but if you go to a 100 book you can see HP is lower on pet and it hits are weeker. Over all having Garuda crit is really good, and dots do crit. In like turn 11 my dots are doing 1,1k each tick not including crits, shadowflare 100-200, and Garuda is 350, but crit is over 600.
It takes 8 det to= 1 int. So you would needs lots of det to make up differences of that crit for SMN.