Alright, so I've modified Quadro 473.81 drivers (using K2200M template + Disable Telemetry, MSI mode tweaks), uninstalled old drivers via control panel & cleaned leftovers with DDU in safemode, resetted, and then installed these drivers and they work! No problems shown in device manager, GPU-Z shows the right info, and Optimus works (tested JC2, activity icon signalised usage, and benchmark reported the Quadro card being used).
Thx to all, and especially Stefan for creating this guide!
After looking exactly at all reports from DELL users i think we can isolate the R470 issue to the Alienware M17
Pesky if you paid a grand alone for the GTX 880M chip
I update the 1st post to reflect that...
Oh, will also test that. BTW, what template did you choose? I was using the K2200M template as the difference between K2100M's and K2200M's sections in release 426.78's inf were marginal, but not sure if there's a more suitable section/template compared to it.