Morning update:

BeOS R4.5 installed "like a glove" yesterday. The only thing I regret is not doing a clean install, because I think there's some old stuff hanging around that I don't need any more. I'm probably going to re-install it again tonight. Hardly a big deal, since it only takes 15 minutes :-)

It seems faster than R4. There was one annoyance, with the sound recorder app. As soon as I opened it, I started to hear a loud "click" in my speakers... repeating every 3 seconds or so. I couldn't figure out how to get it to stop, so I rebooted! :-)