Have a Lumia 950 (dual sim, unlocked, US, T-mobile). Came with build 10586.0. Upgraded with public update to 10586.29, got the first firmware update, updated with Insider to 10586.63, and again to 10586.71. I did not install from back up and never did a hard reset.
10586.71 runs very smoothly. Most noticeable improvements for me has been performance in Onedrive, File Explorer, and Groove Music apps since build 10586.0 (and whatever version those apps were at the time). Also, phone use to randomly restart, apps used to crash once in while usually only on the first you try to open it, and apps used to stay on "Loading..." screen for a few seconds in older build before actually opening. I don't have those issues anymore since .63 build. Poorly optimized apps like Spotify is still plagued with the "Resuming..." screen when switching between apps. However, no battery drain issue ever. Bluetooth works great on some devices but struggles connecting to some.
I did have a ridiculous battery drain issue on build 10572 on my HTC One M8 (first W10M build on it), but it is fine now on build 10586.63.