I'm using it for stereo backup recording with my Mixpre 10II. I'm the reason it recently got added to the compatibility list. I haven't seen anything else that fits the bill this well and is actively supported (and the developer is very responsive). It looks like there's an issue with the 6II and 10II (and possibly others) where it can't see all 12 tracks, so only two are available. I went down the rabbit hole with the developer and it seems to be an issue baked into Android that has to do with USB mode switching. Sound Devices info seems to indicate this problem is specific to the 6II and 10II, noting that those devices require a driver on Windows machines in order to operate as more than a 2X2 interface. There are no mixer/gain controls available in the app. 24 bit is available but not 32. I saw up to 96kHz available, but 192 may be available as well since you have to switch and restart the MP to use it. Stereo input is available in both USB modes but stereo output is only available when running the MP in "normal" USB mode. Streaming apps such as Mixlr and Larix Broadcaster work with or without USB ARP installed (but haven't tried running them at the same time: USB ARP suggests it is not recommended to run it in the background).
Hope that helps.