Sorry to be the bearer of bad news
I'm quite happy with my 11R, but mostly use it "live" more then recording.
I'm not sure what would be causing any signal issues with your SPDIF connection, and while I have no doubt that a good cable is the way to go, we're talking 1's and 0's here, if one of them doesn't arrive properly it would be quite noticeable with pops or dropouts, not like analogue where you'll get hiss or unwanted distortion.
Joel