We just purchased an IP Office system with 9508 phones. The speakerphone quality is nowhere near as good as the 4412 phones from our old Magix system. If you plan to talk on speaker a lot you will find it very annoying, and more so for the person on the other end. There's an Avaya bulletin regarding the new R38 phone FW that acknowledges the problem but no fix yet.
To add insult to injury, we've also been experiencing isolated situations of very loud digital noise and distortion through the speakerphone. Seems to be in conjunction with whenever someone's talking. Not too happy with the experience so far. I would give up full duplex in a second if it improved the sound quality to what it was on the 4400 series phones. We had no idea how good we had it, until we "upgraded".