Was previously running builds in a VM and updating from the beginning, but pulled down the 9926 ISO, extracted it with 7-Zip and ran the upgrade directly on top of 8.1 with appropriate, advance precautions on backups, images, etc. Upgraded in less than 30 minutes, it's now my production OS on my SP3.
Couple of more updates after that, then ran Wise Disk Cleaner and disk clean-up to get back about 23GB of drive space after siphoning off the ISO, its extract and Windows.old to a jump drive first.
Some nominal fan for about a half hour after the upgrade, but no jet blower, ran some Youtube videos in all of IE, Waterfox and Canary and they were all fine. I'm on the 01/15 Intel video drivers, no problems.
System does seem snappier so far.