(In reply to bamnell from comment #7)
And btw I tweak those settings, know what I'm doing, and DON'T use nightly because I need a stable browser not one that might break next update, had that happen
And also chrome://flags is not restricted to Canary why should about:config be restricted to Nightly?
And it's not just experimental features there it's just really more advanced settings.
Another thing is that multiple profiles aren't really supported on Android, and multiple installs of the same application package aren't possible at all.
The former is a problem because I might like to keep separate profiles for my normal browsing and for experimental testing, and in the absence of real profile support it's easier to just keep Nightly completely for experimental browsing and testing, and use Beta or Release for my normal profile (where I'd still like to tweak some things that aren't possible through the UI, though).
Perhaps even worse is the fact that you can't have multiple installs of the same package, so whenever I need to track down a regression via mozregression or by doing it manually, I have to uninstall my current Nightly (or sometimes Beta) in order to replace it by the Nightly/Beta version I want to test. With the way Android works, doing this also kill all previous app data, i.e. my browser profile. At least personally I use a rooted phone, so can at least restore a full backup of my original profile afterwards, but that's not true for everybody and still somewhat of a hassle - and Sync still needs to be manually reconnected afterwards anyway, which is even more annoying (especially during the time when my former e-mail provider used to randomy greylist the sync confirmation link mails for hours).
Hence one more reason not to use Nightly for regular browsing on my phone.
As for the kind of prefs I've modified,
- occasionally played around with some of the
font.size.inflation.* tweaks beyond the main pref that can be controlled via the regular settings
browser.sessionhistory.max_total_viewers back when it was still set to
1 by default because the original Fennec ran on a phone with only 128 MB (!) RAM - and while I also tried it Nightly, being able to tweak this in my main profile (not Nightly, see above for why!) as well and and observing its effects was one reason I finally submitted a patch for increasing the default value
- some of the
apz.* scrolling behaviour tweaks
apz.one_touch_pinch.enabled when it was temporarily disabled on Release because of some bug that didn't really affected me
network.trr.mode if it starts interfering in unwanted ways with my DNS configuration
ui.scrollbarFadeDuration because I think the scroll bars disappear too soon by default, and also look nicer if they actually fade out instead of directly disappearing
view_source.wrap_long_lines before I eventually submitted a patch to change its default value to true
and some things that are rather Fennec-specific and not directly applicable to a GeckoView world, but still examples where having about:config access was useful
browser.sessionstore.max_tabs_undo (I prefer a slightly larger value than the default)
browser.tabs.useCache (never permanently enabled on Release because of some major bugs for some users which nobody had the resources to ever track down, but for me this works well enough to keep it enabled regardless)
- Fennec does its own default app selection for downloading, but we never implemented a UI for resetting those choices, so the only way to do that is via about:config
- getting some session store debug logs from regular Beta/Release users - it's already bad enough that accessing logcat logs isn't exactly easy for normal users (and the move to Webextensions killed jchens useful add-on), but at least that way the could use their normal browser and didn't have to install Nightly as well
- disabling automatic add-on updates, because unfortunately on Android there's no UI to manage updates per extension, so if you have >=1 extension that you want to keep on a specific version for whatever reason, the only choice is to completely turn off updates (but at least you have a choice)