Had my brand new BM789 (from welectron with dakks calibration) for a week and I just want to share some info.
Firmware version is 13 so I guess they are still making improvements.
BM869s seems like a mistake as BM789 is better for AC voltage (more accurate voltage up to 100kHz - both meters go higher than that) and the readings are way faster (BM869s needs a few seconds to stabilize).
BM869s has the edge only in AC current but BM789 is not that far off, even if the datasheet lists only 3kHz it goes almost as high as BM869s.
I strongly recommend lubing the rotary switch as it's quite bad feeling out of the box. Super lube works perfectly.
Now for the those that like to compare backlight duration.
Every DMM that I owned switched the backlight throw a transistor so you could replace it with a resistor to limit the current and have the battery last longer with always on backlight.
Why do Brymen meters have backlights as bright as a flashlight ? If I want a flashlight I don't use a DMM
.
The BM789 is a bit special as the backlight is connected directly to the battery so it's not going throw the rotary switch.
The only way to have always on backlight is to get a voltage to the base of the transistor that is switched from the rotary switch (luckily there is a 3.5V track next to the transistor base track).
The mod can be done without removing the screen (just the plastic that holds the screen and backlight board then remove the backlight board with care) and is doable on the front or the back of the meter (I recommend cutting the transistor base trace and attach it to the 3.5V rail).
Anyway, around 60mA with default 150R resistors (R57, R58 and R84) and 17mA with 500R resistors (the result is more than enough backlight).
Even with good environment lighting the backlight makes the screen more readable.
Maybe one day Brymen will copy Uni-t
(UT622 LCR meter with color screen and backlight adjustable from keys is just perfect or maybe UNI-T UT181 but I don't own one to be sure the screen is good).