Actually I got a nice reply from them, here is a basic summery of the main points. In terms of the arm locking system, being able to trim with a screw seems like a good solution. The problem with the gryphon frames is once the arms start to have a little slop in them there isn't really anyway of adjusting it. They seem to have a solution for that.
"Our boom locking systems is really reliable and tight.
There is a safety pin which safe-locks the arms but there is also and excentric fastener that takes away the loosening.
The initial tightness is trimmed with a M3 screw, and once it is done, you can have hundreds of boom removals without any problems.
The standard boom length is 330 mm. With this length you can use 18 inch propellers.
Sometimes customers want longer booms to fit 20 inch props so we just cut them longer.
Motor to motor diagonal length is 800 mm.
The frame fits 2x 16000 batteries and also 2x 22000 mAh Tattu batteris.
We can't say anything about other brands, because we have only been using Gens Ace and Tattu.
The cover gives you possibility to fly in rain and snow.
Our helis come with detailed assembly instructions and you get to know your gear inside-out that way."