After a few more days, 10130 is starting to grow on me. I used it for a fairly long stretch yesterday evening, and it performed pretty well and didn't get overly hot. The only thing that kicked on the fan was having multiple IE tabs open, but the fan was only running about 25%. Seems decent enough, and proves yet again that you really need to let the initial setup/indexing/alien replication processes finish before drawing conclusions.
I can't use tablet mode because of the missing swipe-down get to get to settings and app commands in Windows apps, and Windows Explorer still crashes every now and then, but overall it's a good experience. And I can say exactly why, but Win10 just feels better to me than Win8.1. It's not as efficient as a pure tablet as the iPad, but of course it does 10X as much. I use my iPad for the most ad hoc sessions, but when I'm ready to do real work, it's all SP3.
Overall, I'm getting a little more confident that the July 29 date is reasonable, especially now that they're locking down features and focusing on bugs and fit/finish.