No, the latest version of OWB is crashing my system during a Wikipedia or Facebook session. Renders both my system and the wireless ethernet box completely useless. Icons will go missing or behave improperly too. Have to reboot after letting the computer AND the wireless card sit for a while. It's very aggravating.
That's really very odd. I would really suspect a very screwed installation of even hw issue. I say that, because i haven't got any other similar report, and my mac mini machine (running latest OWB) has a 3 weeks uptime, now, and it involved youtube, facebook, random browsing and so on...

Anyway, do like piru said and run a vanilla MorphOS 2.7 installation to begin with.
Oh, and about MAME (since i also did the port), it's also funny you don't get it to work. Actually, i haven't tested vector games, but many others like neogeo, cps1&2, psikyo and so on, and they work nicely, especially on a macmini. Maybe you just have wrong rom sets there.