I received the G91 today along with a pair of DSP5500 and set it all up this evening. I have to say I have not noticed any harshness even straight out the box. The G91 is a little temperamental while playing DVD-A discs but my friends G98 is the same. I'm using it as a surround system with 5500,5000 and a 5000C. As discussed before I think my sub is no longer required as the 5500's seem to have plenty of low down drive. I'm quite impressed with the surround aspect. Having just took out the 568/598 and replaced it with the G91 I am more than happy. I only used 2 or 3 presets on the 568 so I don't think I will notice any difference. I also noticed the G91 was upsampling my CD's to 24/96 until I set it as a surround system. Now it's stopped doing it? The tuner is great and I have not even moved onto the video side yet as I'm still waiting for cables to show up.
Cheers Gareth