There appears to be a lot more difference between the 997 and 990 than just HDMI switching/conversion. To me the EQ room correction feature would be the most compelling reason to go with the 997.Video scaling in the processor may or may not be helpful as most TVs and disc players do that already with varying degrees of success. The ability to decode high resolutiom sound formats might be important , particularly if you feeding blu ray and SACD signals from different sources.
Having said that, I plan to stay with my 990 for the forseeable future, probably going with the soon to be released OPPO to handle the SACD/blu ray audio conversion and video scalling problems and live without EQ for now.