5.1.1 has been out for awhile and its just getting pushed to the S6's now (in the US, a few carriers had them last month.. I think even late August if I recall correctly).
There's usually 3-6 month lag time between announcement and roll out. Some carriers are good at pushing it out quick, others not so much. This is my first major update since jumping from Telus to MTS (5.1.1).. I'm happy with the turn around on it - is on par with most of the US carriers. I'm pretty sure KitKat to Lollipop was about 4 or 5 months from announcement to release (at least on the S5 I had)
But maybe we'll get lucky and MTS will surprise us ;)
US Carrier T-Mobile actually has a nice site that lets you check on the Marshmallow status for specific devices. As mentioned above it can vary hugely on when it actually lands on MTS devices but it is a good reference point. If it hasn't even entered the "T-Mobile Testing" stage chances are pretty good it has not been released by the manufacturer to any carrier yet.
Here's some outsider information on the Marshmallow updates:
I hope you all enjoy your Thanksgiving weekend!
In terms of the G3 specifically there are three different versions, one of which is specific to Canada. Searching the Internet as of a month ago none of them have a Marshmallow release available.
Samsung has reportedly released Marshmallow for the S6 and S6 Edge in South Korea. No word of which of the many different models it is though as the S6 alone has at least four regional variants.
Edit: Seeing reports this morning the Note 5 Marshmallow release has entered testing the US.
In the mean time MTS, how about some security patch updates for our Android devices, rather than waiting for Marshmallow to fix those.... Still sitting with November's on my Note 5. These are a monthly thing available for Androids to keep them secure!
It will at least upgrade my device's security patch level some...which BTW haven't heard anything about (the lack of the monthly security patch updates being pushed through) by MTS..and I've voiced concerns a couple times in the forums here...
Good news everyone, the long awaited release of Marshmallow for the BlackBerry Priv is happening next Tuesday.