While the Mi engine is better, the E engine is certainly adequate for high altitude operation. I did not adjust the carburetor between sea level and high altitude, it would climb to 13,000 ft. well and begin to run a bit rough between there and 14,000 ft. I have calculated the climb rate for the first 1000 ft on all of my flights out of Truckee (typical density altitude at takeoff is 8800 - 9200 ft.). With the E engine it was around 430 ft/min average, with the Mi engine it has been about 550 ft/min. It out climbs a Pawnee towplane towing a similar glider. My E engine had the original Technoflug prop, however comparing Technoflug and AS props, the climb rate is similar (acceleration is better with the AS). Climb rate at sea level is over 800 ft/min.

On Friday, October 2, 2020 at 8:47:35 AM UTC-7, waremark wrote:
Yes to the difference between the 26E engine and the Mi engine. I had a 26E and have flown a 31. If you operate in the flatlands the engine upgrade is not a reason to change, at low elevations the 26 has good take-off and climb performance (better than the more powerful and injected Arcus M which I fly now, but not as good as the DG 808). If you might need to cross high mountains the injected version would be much more suitable (there is no in-flight mixture adjustment on the carburetor 26E version) and of course the extra power is appropriate for the heavier 31.

The Schleicher gliders have used fine pitched propellers for best take-off performance since a few years after the 26 came out - the quoted ground roll reduced from 300m to 200m (from memory) when Schleicher changed the prop from the original Technoflug prop to their own prop. If you want to fly level under power for your self-retrieve the Arcus cruises faster than the 26, I presume as a result of a coarser prop.