I'm the one that bought Wimpanzee's .22 Sidewinder, and sadly I pretty much have to agree with him - except I don't fear the action . . . but agree that it is nowhere near as robust as my .22 Huben despite the similarities. It is loud - even just from the action cycling, and I don't know why (the Huben is so much quieter in this regard). I did swap out the factory moderator with the 1/2 - 20 adaptor from AoA and the discharge sound is now well managed by my Huma 40 Compact, but the action is so loud, which is made worse by having to put your head on it. With both the Sidewinder and the Huben at the same power level, the Sidewinder is a good 8 dB louder than the Huben, both with good moderators on them (the Sidewinder is now a good 5 dB quieter than it was before). I do not find it to be "backyard friendly," while the Huben is.
I'll say that I don't think there is anything wrong with this particular Sidewinder - it shoots great and does everything they say it should. It just does not do it as well as the Huben does (I can even get two shots off with the Huben as fast or faster than the Sidewinder does in full auto, as the Huben trigger resets with just 1-2 mm of movement).
All that said, if I did not have the Huben I think I would be blown away by the Sidewinder as a well functioning select fire gun - I would just attribute the shortcomings I see against the Huben to the different functionality of the gun. But I can tell you that it is lacking when compared to the Huben.
I'm not unhappy with the purchase - in a weird way it made me love an appreciate the Huben even more. I'm still working out what I want to do with it, but if something ends up needing to be sold off, the Sidewinder will be the first to go.