The Gas/Glow mix was invented to be able to run engines on glow (OS "F" in this case), however with the new OS G5 "Gas" glow plug this is no longer necessary.
I have experimented with the OS G5 and the NGH GT9 and it works, carb settings are only slightly richer than on EI.
No problems running with muffler pressure but I prefer a pump, I also use higher content oil (15:1), I just feel it is more appropriate for a non bearing conrod in spite of what the manufacturer suggests, performance difference is negligible..