I wouldn't compare the oil consumption of the EFI to any of the ETEC, 850 or otherwise. The 600 ETEC is an absolute miser when it comes to oil use, unless you're really laying into it.
Does the 600 EFI have similar markings on the adjustment plate as other oil injected engines, min and max?
That's definitely a lot of oil. My old 550 wouldn't even burn that much even when hot out.
There is a wild difference in oil consumption in 550s and 600HOEs between sleds or model years or type of riding. The 600HOE for example was a miser on oil for many years, but it changed in the later years when BRP bumped the power. The 600R wasn't just a bump from the original 115 Hp 600HOE to 125-130 Hp. As per independent dyno tests that were following the 600HOE, it did see a progressive increase in power in the later years such as 2016+. When taking a closer look at the original 2004 600HO SDI, they were reaching an oil consumption as low as a quart of oil to a tank of gas for roughly a 70:1 fuel/oil ratio, and they were also dropping engines! If you look carefully at all the engines in the early REV and the ones still employing the ZX chassis that were mostly carbs, but all using the latest oil cable adjustment, BRP had been lowering the oil consumption. That did not last long before realizing it was not working. At the same time Polaris was dropping the oil consumption on their 600s in equal or greater amounts! When looking carefully at the 600s in the past twenty years, Arctic Cat, BRP and Polaris, have all raised the oil consumption. So if we are to compare the latest Ski-Doo EFI, we also need to compare with the latest 600s.
While I have said the 600 EFI appears to be using a lot more oil compared compared to the higher power per CC 600R, there is also a need to compare with the power for a given rpm/load. For example, even if a 600R can consume X amount at 8,000 rpm under full load, a comparison needs to be made closer to what the EFI can accomplish at say 6,000 rpm where the power output is closer to one another.