Are you saying the 500 GB EVO is a no-go? After lurking this thread for ages, and discovering that Tarkan's mSATA adapter was on pre-order, I decided to go and buy all the parts I need. Which included said EVO.
Also, the 2000 mAh (Alex's) battery everyone's talking about, would that be this one? http://www.ebay.com/itm/2000mA-Battery-Back-Cover-Upgrade-kits-replacement-for-iPod-Classic-160GB-thin-/191194956202
I wanted to thank everybody in the thread for getting me on the modding track and providing such a treasure of info. I do agree with SirMarcoline though: a wiki, or an updated front post, would save a lot of time.
One last question, I've seen mention of a Beyondwind Rockbox. What makes it different from the regular Rockbox, exactly?