In the absence of evidence I'd be inclined to agree that it is more useful. In terms of having that fundamental understanding of science before being taught the actual medicine, i do think chemistry is the most useful science. If you aren't familiar with what e.g. ions are, or hydrophobia/hydrophillia, its hard to then build a good underlying understanding of physiology, and without that you may as well put everyone on a 2 year PA course and save a load of money.