I tried it with 2.1.0, cause then I could clearly see the 401 error that have been fixed in 2.1.2.
Sync speed at 250 gave no errors, sync speed at 275 did. Then I tried 265 and I got no errors, but when I wanted to try it again it was automatically updated to 2.1.2. So my backup plan would be to check the log and so far no issue. I think I will set it to 240, then I have a poll ratio of 15x hour (360x per day). Enough for just roller shutters 
The weird part is that during my tests I suddenly had to switch to OAuth on, while I was always on the old method. So maybe Somfy is upgrading accounts to force OAuth? If I didn’t use OAuth I received:
