I've also noticed a big difference w/ Katrina...size of the eye. When Katrina finished the first ERC the eye was huge which is systemic of an annular hurricane. This allows a storm to more closely approach its maximum potential (ref Isabel, Ivan, Frances at cat5...all had very large eye diameter) as well as larger time frame for the eye to "contract" and pressure to fall...thus not as many ERCs and slower weakening. Note that Katrina only had 1 ERC in the gulf which resulted in the huge eye and did not go through another one. It will be interesting to see what happens after the first ERC and if we get a larger eye as a result with Rita...IMO I dont see this happening