I have the four core model; I'm not sure for my work flow that faster CPUs or more cores would really help much compared to the cost. My SSD upgrade has really given it new life in terms of responsiveness.
Thanks for the link to the workaround. Hopefully it isn't something that will get broken with updates.
Yeah, I'm a little concerned about updates breaking things. The good thing about this hack is that you don't have to modify your installed OS X system. If I understand correctly, the Chameleon bootloader emulates EFI64 and fakes OS X into thinking you booted an EFI64 system. So I think the likelihood of updates breaking things is much smaller than that of Hackintoshes, for example.
Nevertheless, I'm going to try to make sure I have a full backup before doing any major OS X updates. I also have both a Lion backup (as well as an old Snow Leopard backup) that I can boot up in case I need to.
Thanks for the link to the workaround. Hopefully it isn't something that will get broken with updates.