I took time to compare the descriptions of USB controllers inside LPC18xx with that in LPC43xx. I could see no differences after 20 pages, so I stopped. Since I'm in desperate need for a hi-speed USB host with even more computing power, I'm thinking to extend the current nxpUSBLIB edition adding LPC43xx support by simple copying of LPC18xx configuration stuff.
Maybe, I'm wrong and there are real differences between the two device families as far as the USB is concerned. So let me know that.