Technically, the Model 997 was based on the R972, and the Model 997 was not released because of operational issues and limitations with the R972. Some of those have been resolved (through firmware updates over the first year or two of the R972's life), but I don't think they were resolved to a level that Outlaw would have wanted. From that perspective, you could find the R972 to be a step back from the Model 990 operationally. I don't think sound quality was ever an issue, though. I also read some things on AVS a while back suggesting that the Trinnov implementation wasn't 100% on target, but it did seem to be close enough to be fairly impressive.