I did a test last weekend and totally agree with Huegelreiter that the tyre compound is the most important factor for rolling resistance.
I tested one of the fastest mtb tyres tested by BRR, the Continental RaceKing Protection Black Chili Compound 2.2, front and rear, rolling down a fire road, and it was a lot faster rolling than my previous tyres, the Pirelli Scorpion XC RC Lite 2.4’s.
Immediately after I tested Kenda Rush Pro SCT 2.4 front and rear and these were a little faster than the Contis, while having bigger knobs.
If anyone is interested, I posted the results on the MTBR forum under the race tyre thread.
In short, the Rush compound seems to be great, which should result in low rolling resistance BRR drum test results.