Cayenne, I have a Kamado Joe I just picked up a couple of weeks ago and have been cooking steaks on it successfully using the two level direct/indirect set up. I let the cooker come up to 500/550 and sear the steaks over the lower, direct fire for about 1 minute on each side with the top closed. Then I move the steaks to the higher-indirect side and cook to an internal of 125. I use a Thermapen to check temp. The steaks I cook are also ~1.5 inch thick and they have come out perfect every time. I've done rib eyes, bone in and boneless, and NY strip.
Here is the first one I did, this one was a little thinner than 1.5", but I followed the same method:
