I was on M050, rooted via Kingo, OTA prompt showed up for me yesterday:
- update via OTA failed twice, even after reboot and remove battery (this was true in last upgrade to M050 as well)
- unrooted via Kingo, took the update via the PC-based update tool, after the update said the phone was up to date, but also said a repair was available (it did this when I updated to M050 too)
- took the repair twice without the repair available message going away (it also did this when I updated to M050, and since then has always told me a repair is available that doesn't get "fixed" by accepting the repair, but, I also have had no problems I'm aware of related to whatever is being detected as being in need of repair)
- then successfully re-rooted again using Kingo
- Phone says I'm now baseband/build M070, still Android 4.1.2, Kernel 3.4.0 (Hardware ver 1.1). Lost a couple widgets in the process, during some reboots got a couple error messages abt things that weren't available before LinktoSD got running, needed to do an update of SuperSU, but after a couple successive reboots to put everything back in place with the phone "knowing" it's rooted, LinktoSD running, etc., all seems to be as usual and problem free, though haven't done any formal testing nor yet used the phone much.
- I don't notice any particular difference from the update, other than the start-up logo is changed, but again, haven't really gone exploring.
EDIT: One other other slight difference I noticed, after the update, on the first reboot (only) after update, and then again, on the first reboot (only) after rooting (which made LinktoSD available and therefore additional apps not previously available, available), it went through all the available apps and "optimized" them, whatever that was doing - again, no difference I noticed due to the optimization.
EDIT 2: All looked fine until I rebooted the phone, being rooted seems to "stick" (tho I"m not entirely sure, have been a couple times where I've lost that, not sure if that's b/c it wasn't sticky, or from my fooling around w/superuser as below), but superuser (via SuperSU) doesn't stick, each reboot says the binary needs to be updated, and says the update was successful, too, but SuperSU is at the moment ver 2.16, and rootcheck shows the binary as v2.15, and, each reboot the whole thing happens all over, w/no root access until I (pseudo)update the binary - the updated binary somehow doesn't get permanently written (or gets overwritten by the OS each reboot?). Haven't tried it yet with any of the other/alternative superuser apps.
