Recently I purchased some of the new Gemfan 2040 "Hulkie" props to try on my lightweight EYAS X2 build (more details on the build here on rotorbuilds).
The props are well priced and sold by many vendors now. I used banggood as they offer free international shipping which is especially handy if, like me you live outside the US.
I'll be comparing these a lot to the Gemfan 2035 4 blades (cheapest on Gearbest at present) which have become the defacto standard for performance and durability in 2" props. Here are the key qualitative differences I've found:
Blades are less durable. The material of these blades are more rigid and seemingly more brittle as a result. It takes a lot off effort to kill a 2035 on a light quad but the hulkies seem to like snapping at the hub as in the pic below. Additionally they chip at the tips which the 2035s don't seem to do. Note: they are still much more durable than the king kong 1935 props which although good and well balanced can explode just by staring at them too long. Last pic is where I flew on Tuesday morning rather than working. Shhh.
They are well balanced. Not much else to say here. They are on par with the 2035 and the king kong 1935. Don't underestimate well-balanced props even on a 2 inch quad - I've had some shocking 2" props (looking at you racerstar)
They may be able to handle more powerful motors. Although more brittle, these props are noticeably stiffer and I'd expect they will be able to handle a more powerful 11xx series motor better than the 2035 by not flattening out at high rpm. This is only a hypothesis though as I prefer a larger prop/frame when using bigger motors than an 1103.
Efficiency/lift feels similar to the 2035. Gemfan's data at the end of this review suggests that the hulkie props generate more lift at the same current compared to the 2035. Purely from my subjective feel they seem to hover at a similar throttle, have a similar punch out power and get a similar battery life to the 2035 - certainly I couldn't pick up a real difference. Note: my quad is very light at 40.5g dry, 58g with 2s 300mah battery. Interestingly the hulkies have a wider blade than the 2035 meaning the total blade area for each prop is roughly the same.
Hulkies are louder. New hulkies are louder than the 2035s and louder than what I remember of the king kong 1935 props. Not 5" loud but not quite as stealthy.
They have a slightliy bigger diameter. The 2040 version of the hulkies has a slightly larger diameter than the 2035 which is already a hair over 2". No problem if your frame has plenty of clearance but a big deal if you have a frame like the flex ascent v1, x2 elf, x2 eyas and others. At least there is another option - The Hulkie 1940 which has less thrust but less current draw as well as being physically smaller. I have not yet tested so it would be hard for me to comment further on these.
So, my overall verdict? I tried these out after getting bored of the Gemfan 2035s since they just didn't break. The 2035s bend on crashes and I'd bend back, good as new whereas the hulkies usually bend half the time and snap the other half. In the real world the performance of the gemfan 2035 and hulkie 2040 is similar but the durability of the 2035 wins it for me. Only reason I'd stick with the hulkies is if I crashed less (not happening) or if I have more powerful motors than needed a stiffer prop.