Yes, I've been able to install 10166. Using Windows Insider, Fast Ring and Update phone.
In conjunction with Windows 10 launch coming up in 9 days time, i'm gonna use my L535 as a daily driver (for the first time since switching from 8.1 to TP10) and see how it goes from there. After giving the significant other my 32GB card with the BlackBerry Z30. Took quite alot of convincing to put away my 1+1 for the time being.
So I got myself a Sandisk Extreme 64GB to compensate for the lack of internal storage space. Finally have got everything sorted more or less. Some of the issues i can recall i'll list below, if there are fixes or workarounds do sound out.
1. Instagram Beta doesn't work - Fix : Use 6Tag
2. Box doesn't work - Fix : Use Dropbox and Mega
3. Keyboard seems to get better over-time, it was really sensitive at first. Not sure what changed but it's better now.
4. Apps that have not been updated in awhile or developers who do not actively update WP : Scaling issue, unable to see action buttons.
5. Lumia Camera doesn't seem to be available anymore, seems to be called Windows Camera.
6. Apps that are listed free, when you search the store price tag is still there (could be a region issue)
7. Cortana doesn't seem to have settings as before (at least it's working now unlike the past 2 builds). Remember to set region and language to : US - English
8. When moving apps to SD card, try not to move apps that you frequently use. As restarting sometimes, cause the app to be unavailable. It happened before, fortunately when i restarted again, the apps came back without needing to uninstall and reinstall. Could be mainly an issue with storing apps in external storage rather than the build in particular.
The phone is holding up okay so far, hopefully more apps will come in with Project Astoria it looks pretty seamless and will work across PC. Thought it was like BB10 runtime, but seems to be more native which is good.
That's my update for now. I think it's safe to be a daily driver or seems that way.*Fingers crossed*