Necessary to reserve Win 10?

Always a good idea to post an original source. when quoting.

As Mystere referred to, in post #5

http://blogs.windows.com/bloggingwin...review-builds/

One correction to the lifehacker post, if you keep testing builds you won't need to buy a license until you quit the insider program or the insider program is canceled by Microsoft whichever comes first.

Yes, I saw the notation but it needs to be worded better.

Ztruker said:

I think that flow chart is wrong. I believe you get a free upgrade from 7, 8.1 or 10 preview, not from 8.

The chart is correct. You just can't upgrade automatically via Windows Update. There's another chart that shows which versions can automatically upgrade, and which require an ISO. Windows 7 RTM and Windows 8, or Windows 8.1 pre-S14 all require physical media, but can get the free upgrade.