Well, Ubuntu 13.04 (Raring Ringtail) seems to run much better on a Macbook 5,1 (late 2008) and MacBook Pro 6,2 but it still has issues in that grub doesn’t properly dual boot.
After two boots, the ReFIT I had on my MacBook Pro seems to work properly, but ReFind doesn’t at all on the MacBook.
Looking (chasing) through all the documentation, I found that there is an alternative install that isn’t on the main Ubuntu screen called 64-bit Mac (AMD64) (confusing since Mac’s use the Intel chipset, but apparently this is really the 64 bit build) and there is a character interface install only for servers as well at Ubuntu Release 13.04.
Overall, Ubuntu seems pretty unstable on these two machines. On the MacBook Pro 6,2, it runs fine, but then had a problem and wouldn’t boot. Complained about a bad swap file. I had to reinstall it and it works really strangely with ReFit. It also created the ISO to DMG file correctly
On the Macbook 5,1, things were worse. It seem to run OK when it booted from the USB, but couldn’t build the ISO to DMG correctly on a USB. The exact same thing wouldn’t boot using the same instructions on the MacBook Pro. And also the while it would boot from the USB, when installed onto the hard drive, it hangs with a black screen.
Sigh, reminders of Windows. Next stop is to try not to dual boot but just run Ubuntu with the whole hard drive on the MacBook.