It was worth it for me.
Here is what I noted when I went to the Integra 9.8 with the new HD audio codecs. For reference, I was previously using a Rotel RSP-1068 processor, which I thought was excellent in it's own right-
Bigger, more enveloping soundstage
More depth/layering to the soundstage
More relaxed/natural sound
More detailed sound
I wouldn't call it "night and day" difference, but I was not at all struggling to hear the difference, and it was quite impressive. I was somewhat skeptical at first, but now I have no regrets about rolling the dice on the new HD codecs.
Be warned- it is similar to making the switch to HDTV, in that SD cable stations just suck by comparison (I consider myself an HDTV snob). Pretty soon you won't want to watch movies unless they are Blu-ray discs recorded with the HD audio codecs.
Having said all that, you may be able to get the same or similar results by getting a Blu-ray player that internally decodes the new formats and send it out through the 5.1/7.1 analog inputs. This would be a cheaper option.
On a side note, the Integra also has Audessy room EQ/correction, which I am now a firm believer in- it is a wonderful thing.