I've noticed networking, in general, works better in 7.5. However, using OT 1.2.1 in 7.1.2P seems to work quite well, even if it uses 300-400k more RAM than MacTCP. However, having DHCP is indispensable.

If they could get Wi-Fi working on the PB500 series with a Rev-C PCMCIA card cage on 7.1.x, I'd be really interested, but it has not been possible, as far as I'm aware.