The only difference between the AX and the IIA that I can find is the revolving vs reversing back. The difference in price, however is $539 at B&H. There is just no way that the revolving back is worth that difference in cost even if you really favored it for some reason. In fact, I have cameras with both, and I find myself always forgetting to lock down the back that revolves. The reversing back is locked in from the get go and takes maybe 2 seconds, if that, to change. Go for the reversing back....the AX is a fine camera.