New props have arrived:
GWS Style Slowfly Propeller 9x4.7 Green
Product http://www.rcfair.com/en/product/1082603/

GWS Style Slowfly Propeller 9x4.7 Green
Product http://www.rcfair.com/en/product/1082604/

I'm going to use them instead of the smaller ones, which I have used so far:
8045 SF Props 2pc CW 2 pc CCW Rotation (Orange)
Product http://www.rcfair.com/en/product/510248/

This is the configuration:

Essentially, I had to check them.
All these props are intended for a copter with a total weight of 1,200g. Now the components: a 4000 20C 3S Lipo Pack; motors - CF2822; ESC - Turnigy Plush 30A (they are all so greasy because I scooped them up at Parkflyer, Russia, last June, and they were cheaper than 18A ESCs).

First I held a load test with maximum thrust:

The result made me feel happy, as thrust level reached nearly 850g. However, I also wondered which of the props would be more effective. I measured it with an amperemeter and immediately realized that a servo tester could not reflect the exact amperage/thrust ratio, probably because the tester had too big a PWM width. For this reason, the comparison points are a little wobbly. Well, here is a comparison table with the results:

Based on the results, I built a diagram.
1. Amperage/thrust ratio:

The last figures are approximate, because the bottle would fall off every time I tested the props. Besides, maximal thrust decreased because the circuit included an ammeter shunt. Based on the results, I built an efficiency diagram, efficiency expressed in the gram-per-amper fashion.

Well, I figured out that a bigger prop was also more energy-efficient. The most important thing for me was the 300g thrust, which is quite understandable.

In other words, in the hover mode the copter would take about 14A (including all energy-consuming components), and that was not bad at all.

This is the translated version. You can read the original Russian article here.