The major difference between the SL811HS and the CY7C67200/300 is the fact that the CY7C67200/300 has an internal processor, has more available USB ports, has more internal memory and has alternate processor interfaces. The SL811HS requires an external processor to control it but it is fairly simple to use. The CY7C67200/300 has an internal processor or can run from an external processor.
Since CY7C67300 has an internal CY16 RISC based processor with BIOS, it requires less CPU bandwidth because it takes a list of transfer descriptors and operates on them on a frame basis. Since SL811HS does not have an internal processor, it will require more external CPU bandwidth because it must deal with individual packets. SL811HS has 8-bit interface + cntl lines while CY7C67300 has 16-bit HPI, SPI or HSS interface.
Besides this, there are certain OTG protocols that the SL811HS does not support. As for example, the SRP and HNP protocols are among the few protocols that are not supported by this product.