I like this unit on paper very much, but the 3 modes still seem a bit confusing to me, and I hope that they are changed a bit in a future firmware update.
The way I'd want to use this is for recording something like an orchestra or chamber ensemble, with a main stereo pair on channels 1-2 as a linked pair, and two solo spots on channels 3 and 4 individually controlled, with no L/R mixdown. I also want to be able to quickly adjust all of the gain levels from the 4 channel knobs. Strangely, it doesn't seem possible to do all of that in Advanced mode. To adjust ISO gain in Advanced mode, you have to press the channel fader to go into that channel menu, then select Gain, then use the headphone encoder. Moving the channel knobs in Advanced is adjusting fader level for the L/R mixdown; not ISO gain, which you have to go back into the channel menu to adjust. To get ISO gain control from the channel knobs and channel linking, you have to use Custom mode.
In the video below at the linked time (2:47) he demonstrates the bug a few have mentioned where deactivating the L/R track while Gain is set to Basic causes the ISO tracks to record at very low levels. This would make the recording situation I described above not possible until this is fixed.
https://youtu.be/XAaWUbCpCPg?t=167Possible bugs aside, wouldn't it be far simpler if Custom and Advanced modes were combined into one mode? Right now, you change to Custom mode and set Gain to Basic to control your ISO gain from the channel knobs. This doesn't really describe what is happening. Instead, I'd like to see a submenu in Advanced called [Front Panel Knobs] with the options [Channel Gain] and [Track Fader]. You could also have a shortcut toggle between the two modes of knob operation by holding down the channel knob, you then are in the other mode which is indicated onscreen and with a flashing LED ring, you long press the knob again to toggle back. That might be even easier.