I am getting 6 of the 8500W openers. A lot of people mentioned some of the concerns. They are not perfect.
Here is a pretty good article from Liftmaster talking about the 3800 and some things that they have learned.
https://www.liftmaster.com/catalogr...ed/files/tucmanuals/isbgdo3800 door types.pdf
High lift tracks were mentioned as well as pusher springs or doing a slope to the track so it isn't completely horizontal when up. The problem with jack shaft openers in a sectional door is that they simply turn the torsion bar or jack shaft. If there isn't anything there to help get the door moving meaning the pusher springs or gravity, then you have an issue where the jackshaft turns, the door doesn't move and the cables unwind leaving you the birds nest that was mentioned above. Pusher springs at the end of the track help push the door down to get it moving for the first foot or so. The other things that help are the high lift track because the lowest section or two is always pretty much hanging so that gravity can help with getting the door moving.
As others mentioned the 8500W does come with an internal battery backup. So you can still get in when there is a power outage.
They have an electromagnetic dead bolt. So if someone tries to force the door open they will only be able to open it a couple inches depending on how it is installed.
There have been issues with the doors opening on their own randomly. Not everyone has this issue, it seems random, who knows why but I will say this much. All reports that have seen really point to the 8500. Not the 8500W and as mentioned above the 8500W has a different wall mounted switch. So maybe the issue is with what they are shipping with the base 8500. Some of the main differences between them is that the 8500W has wifi built in for the MyQ stuff where it is an optional addon for the 8500. The 8500W has an LED remote light and the wall mount control is different. Cost difference is about $100.
For my garage build I am going with high lift tracks if possible and add pusher springs if needed. Haven't gotten a solid number on ceiling height yet as it depends on where the slab comes in and matching with existing roof line as we are doing an attached garage. It should be about 10' at a minimum but more likely closer to 12' at a max. Depending on that ceiling height number will dictate 8' or 9' tall doors.