Howe accurate is hotslogs/heroesprofile hidden QM MMR?

[Sunwind 0]

According to HOTSLogs I am "Platinum 648 (MMR: 2142)" in QM

And HeroesProfile:

 

GM in QM? 

 

Been playing 7 months now. I mostly only do QM.

[Archorn 0]

Haven't used hotslogs for a few years now and never used heroes profile so can't really say how accurate they are at the moment but the way they work from what I can understand/remember is that they take (parse) the information from replay files that players themselves upload and base their "mmr" (and other stats) on the information contained in those replay files. (As long as one player in a game uploads their replay file they get the data for every player in that game which is why they can have data on you even if you yourself didn't upload any replay files.)
This means that the more complete their records of replays are (i.e the more data they have access to) the more accurate their score probably is.
I'm not talking about only your own replays here however because your mmr gain or loss after a game depends to some degree on the mmr of every player in the game (and the less accurate their mmr score is the less accurate your mmr gain/loss will be).
This is one of the reasons (other than learning the game and improving) why your mmr changes so much/"violently" on the left side of the graph when you first start out playing but over time the changes gets a lot smaller/"gentler" as you near the right side of the graph, as you start playing they have no data on your games to base your mmr on but as you play more and more (and they get more and more data from your replay files) the accuracy of your estimated mmr gets better. You would probably see a similar graph (violent changes in the beginning that become more gentle with time) for a smurf account made by a long time player.

I would guess that the most accurate one for your mmr is the one that has more of your replays and if both have a similar amount of your replays then it is probably the one with the most replays from your server/player region overall (since more data means more accurate mmr calculations)

Also from your picture heroesprofile doesn't seem to have a mmr value for GM but rather it seems everything above 2560 mmr is considered Master (which still is impressive)