I got tired of waiting for my Lumia 640 LTE to receive the Win 10 Mobile upgrade. I installed the mobile Insider app and told it to get the latest build. What I got was version 1511 build 10586.107. As far as I could tell this is not a preview build but rather the release build for Lumia phones. I then went back into the Insider app and left the Preview program and switched to production updates. It then suggested I search for updates and I received 1511-10586.218. So far so good but I notice , in my usage, very little difference from the Windows Phone 8.1 Denim that the phone came with. The biggest difference is that now I have the mobile Edge browser instead of IE. The mail program is a little different and I have 3 Office apps, Word, Excel, and Powerpoint. Cortana is different too but since I only use that for searches without the voice function, there's no difference for me. There are substantial differences from Phone 8.1 but I don't really use many of the new functions.
I'm assuming I will not be receiving any preview builds now but will only get normal updates and the full Redstone build when it is released. That's how I want it so I'm satisfied.