Tim, do we have any idea what is required for uploads? Do we have any idea what is required for AGI? How can you make those comparisons?

Kurzweil discusses the hardware requirements in TSIN, pages 124 and 199. His estimate for uploading is way too low - but the exact estimates don't matter much - the point is that uploads require a lot more in the way of computing hardware. That doesn't address software issues, but probably with several orders of magnitude of hardware difficulties come several orders of magnitude of software difficulties.

If we thin-section and scan a frozen brain, it's an immense amount of data, but at least potentially, captures everything you need to know about a brain.

Everything not permanently lost during the freezing/slicing/scanning process. Then all you need is people willing to have their brains frozen. I'm not arguing that uploads are impossible. Just that the timing and economics mean that the project is likely to be a high-investment low-return one. There are easier ways to produce simulated humans.