I recently was stuck with a 2007.0 CDR and no way to burn 2008.0 I figured I'd stay on the safe side and use 2007.0 stage3. So I pretty much went through a year's worth of blockage in two sleepless nights. Got it working, despite not being savvy enough to do anything more than wear down the blocks by emerge-ing in baby steps and forcing with an .ebuild for circularity blocks. Don't have enough experience to know when to mask/USE which to work out a block. I digress. Sorry. I later discussed with kerframil in IRC, and we think maybe a one-liner in the docs that it's kosher (recommended?) to snag the latest stage3 with an older install disk might save some folks some grief. I mean, once you get that chroot-ed environment, you're always better off snagging the most recent stable portage stage3 snapshot, right?... That's not as obvious to a newbie as you would think. :-)
Well, we're about to completely redo our handbooks anyway once the weekly builds become the canonical install method, so any changes now would be moot. And no offense, but you're the first person I've run into that didn't mix-n-match stages to install media. Everyone else uses whatever CD they prefer (including 2007.0 and older!) with the newest stages.