Interesting findings, Lost in Isaan.
I think we could use some charts to compare the fuel burn to the sim values.
I was at a FL490 cruise with 0.85 and had around 21.00lbs/hr on the individual gauges while the sum up gauge showed 17.000 or so. I have no idea if this is close to real, but at least it's far away from the too economic flying with 0.60. Would be interesting to find out which fuel burn rate is closer to the real values there to pinpoint the faulty gauge.

I think if CS alters the fuel burn and the drag curve at lower altitudes, this fun thing will be as realistic as it could be for the placement in the market and the very nice price.