@ -midnight,
There's really no need to install/upgrade Win 10 anytime soon, as a wait-and-see attitude can work wonders. You'll be able to see if other members are having any issues, and if they are, what the workarounds will be.
You've got an entire year to do this in, beginning on July 29th of this year. I'd wait and see what happens first. Preparation is key, and one of the things to prepare for is disaster, beginning with a full disk image of Win 8.1 first so you can recover if the worst does happen when you do upgrade. If you don't prepare for disaster by creating a full disk image first, then you will not be able to recover back as easily to Win 8.1, and that could be a real problem for you.
Don't know yet if Microsoft is going to release an .ISO file of Win 10, but rumor has it this may happen. If they do, that would make it simpler to migrate to Win 10 vs. doing an upgrade from Win 7 SP1 or Win 8.1. Win 10 would then be what is called a clean install and is something I prefer over an upgrade. Anyway, workarounds for creating an .ISO file from Win 10 preview versions are already posted on the Internet, so that clean install option is already available. Microsoft really wants you and others to use Windows Update exclusively to upgrade to Win 10 but I am saying other options are available.
Suggest you take your time with this one.