For the PC buyer mindset....
I liken the ibook to a celeron M or low speed Centrino notebook (like 1.5)
The powerbook is more like the Pentium 4 notebooks that have high clock speeds but poorer battery life... you also have to protect the pb more, since aluminum shows scratches and dents more visibly than plastic. And everytime I have shown someone my pb they have been in awe.
you can choose to run your portable mac with an emphasis on either performance, battery life or somewhere in the middle.
If you must get one now, its your choice what you do... if you can wait till the end of january, you should have more options.
I would say that an aluminum powerbook is just fine used, if you get it in nearmint, especially if you get it with remaining applecare.
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p.s. thanks for sticking up for me, hahaha