This Gremsy LR1 gimbal with Sony ILX-R1 on paper looks as great solution for photography and video under multirotors. And generally that’s great combo but for now some features doesn’t work.
1.The gimbal is advertised that it has possibility to correct horizon drift in ROLL axis. That function doesn’t work even in newest firmware v782. So during most cases the horizon will be oblique or you have to correct it manually and assign for that buttons on your remote controller.
2. There is possibility to set maximum tilt angle down to 90 degrees which is most useful in most cases. But with such setting when you go totally down gimbal tilts 86-87segrees not 90. So to get 90 degrees you have to set in Gtune maximum to 120 degrees but with such setting you don’t know when you have 90 degrees 
3. Generally If you want to use this gimbal with functions from arducopter you should connect it by Mavlink but that mode doesn’t have so many options like SBUS mode.
Generally Airpixel Entire module helps a lot with some drawbacks of Gremsy LR1 but cost extra.
Anyone succeed to use horizon drift correction on any Gremsy gimbal with Arducopter? I have a feeling that this function never worked on Gremsy gimbals.