jrf you are correct--it depends on how you fly. For me the 24 oz tank in the standard position is fine because I only fly 10-15 minutes at a time which is plenty for me. I use less than 1/2 tank, somewhere between 8 to 12 onces of gasoline per flight. I don't fly IMAC but like 3D. I believe the extremely small change in the CG is of NO consequence for me.

The 1/2" change in the CG would apply only if I ran my BME 50 for 35 minutes plus and completely emptied the 24 oz. tank, leading to a dead-stick landing.

In a perfect world, I agree the tank should be on the CG.