Works great! Ended up with a different design, but still good!

I find printing the model at 98% scale (I recommend changing the X and Y to 98% and keeping Z at 100%) which results in a 30.74 mm inner diameter gives it a good friction fit. That way when I move my printer I don't have to worry about the feet falling off. The 50 duro Sorbothane feet are rated at 5-10 lbs each, therefore the max load is 40 lbs. X1 Carbon weighs about 31 lbs; Isolate It! recommends the load be in the middle of the min and max load for the best vibration dampening. Adding the AMS would make the total weight about 45 lbs (AMS - 5.5 lbs, 4x 1 kg spools [excluding spool weight] - 8.8 lbs). Meaning that if you are using the AMS it is better to go with the 70 duro rating for feet. You could also mix and match the duro ratings, 70 duro for the rear and 50 duro for the front. As the AMS is usually positioned towards the back of the printer and the rear is normally heavier as well due to the motors and electronics all housed in the rear. (edited)