I figured that I should also provide an update on my experience.
First off: The exploit that we used to get this onto our devices has been patched and is no longer available - so you will need to wait until the TP officially supports the M8 or until another one is found. I also installed it since I have multiple devices to play with and I wanted to see if the apps I am working on will work properly with 10, funnily enough there are some layout quirks that I need to address that weren't present on 8.1
The M8 running the TP is mostly stable; I have had one instance of the phone just rebooting itself and two instances where I received a notification and the screen would not turn on. A soft reset resolved this both times.
I am not having any issues with LTE or Data not working properly, however I am having issues with the phone getting VERY hot while using Internet Explorer or watching any streaming video (Hulu, Netflix, YouTube, etc). The increased heat obviously indicates the processor is working hard and getting hot, which causes battery life to drop significantly. I am still able to make it through the day without ever worrying about the charge on the phone, but it isn't as good as it was with 8.1 (which makes sense, unoptimized OS and Firmware that isn't talking between the Hardware and Software properly)
The always-on navigation bar doesn't bother me too much anymore, however I think that it is causing some layout issues. The Action Center shows the bottom of the second row of toggles even when the toggles are collapsed, the hamburger menu for the Photos app is NOT in the right place (it actually clips over some text and the top left picture since it is not in the top app bar like it should be), and some UI content is cut off in apps that don't properly scale or implement a ScrollViewer (This is true in 8.1 too, but you could hide the bar)
I also cannot use quick reply to reply to a text from the toast notification, however I can use the quick reply from the Action Center. I cannot utilize the start screen backgrounds (the 730 is having this issue as well as not being able to hide the nav bar)
This is also another known issue, but syncing with the Microsoft Band isn't very reliable and has a lot of issues. I'm still getting all of my notifications, but I can't sync my data to or from the Health App and cannot update the band using the M8 since it can't sync with the band to determine if it needs an update
All of this, and more, has been submitted to the Insider Feedback app already and I'd imagine is probably already fixed in the newest build whenever it decides to release. I'll continue to provide feedback through the app and answer questions here, so long as those questions aren't "How do I install this on my M8?"
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