...Marziano, somehow you keep insisting on this or that, and i don't see the point in doing so.
Arguing just for the sake of arguing probably - it runs across most of mediterranean people i think
Mainline kernels are not supported via Canonical. Actually, i've only seen them suggesting to people trying such out on Launchpad bug reports, when the bug report is slightly...weird and/or hard for them to resolve out the box, or when they don't consider it worths the trouble of tracking down and re-writing the offending piece of code (the work has been done elsewhere / upstream, so why bother...). This should tell you something.
If you run into some creepy underlying bug with mainline, chances are you might notice it way much later. Simple example would be, patches to ext4 or other filesystems that weren't that much great in the first place, and eventually lead to data corruption. Now, this can happily happen with Canonical's own kernels as well, but chances are you'll notice it via a bug report over at Launchpad earlier. Unless you tell me that you're daily scraping the upstream's mailing lists. Also, they're somewhat older, eg. now 4.13 while upstream 4.15, which means more time spent testing it & more eyes to look into things: one thing is a kernel series that's been out there for a few months, and another matter one that was released merely few days ago.
Some stuff / patches aren't available when using mainline as well. Those can be of any nature, and some of them also eventually get pushed from Canonical upstream. Out of my mind, one of the very first things that doesn't work when you've installed mainline is for example ureadahead. Pretty common app to optimize boot times under non-ssd disks.
Last but not least, the 'common' logic says to try using the kernel that your distro provides - unless you're an expert. Why? Because others use it as well, so if anything misbehaves, you can use your good old friend Google to find similar reports, ask other users of the same distro if they experienced the same symptoms, or just check the bug reports for it in the relevant forums / askubuntu / Launchpad and the likes. Of course, with mainline, you can still always use Bugzilla
, but you shouldn't really expect them there to take you by the hand...
Considering my own limitations knowledge-wise, and also my spare time available to resolve potential issues, i don't find really convenient using such as a daily driver for all the reasons described above. Under very special circumstances, and for a limited time, maybe - and then back to the well-known and safer territory. And if talking about using the very latest one available, then i furthermore also don't find it very wise.
I can't (and won't) tell you what to do, and what to not do. I simply told you what I do. Other than that: you are always free to do *whatever* you want, regardless of...'rules' or *no-rules*. Your machine, your data, your spare time, and, above it all, your responsibility to troubleshoot it...the easy way or the hard way.