Neil,
I have the prior version of Start8 installed on my netbook, so I loaded SDC onto it, logged in, made sure Show Betas was checked and guess what? The new Start 8 Beta is not showing. 
ADDED: OK, I found the new Beta at the store and downloaded and installed it. One thing I notice though is that on boot 90% of the time it still goes the the Modern (Metro) UI and I have to click Desktop to get out of it. This also occurred in the prior version and I have the box checked for it not to boot to Modern (Metro).
Also, when selecting items to show on the right side of the start menu in the new Start8, even though I turned Recorded TV off on the list, it still shows on the start menu.
Oh, and why can't the number of icons to show be set to less than 10?