Prepare for ramble:
I got the .30 sidewinder because I thought it was really cool, nice power out of a semi auto airgun and the full auto is a bonus. Now I've shot it at the range and hunted with it for a couple of years and now I think it's really cool with a nice platform, awesome action, is reliable and accurate, and is really cool.
So I just got a Mordax too and it's turning out to be awesome as well. I can share the magazines between it and the Sidewinder and have all sorts of fun at the range and there is overlap in the game I can take with them. Super portable too
Yeah they are relatively expensive. Also, they use a lot of ammo because they are so easy and fun to shoot. I guess that's a couple of negatives. For me the positives greatly outway the negatives so far. Maybe I haven't gotten 4 grand worth of enjoyment out of these guns yet, but I've sent thousands of rounds down range with my Sidewinder so far, and that would have been way more expensive if were some brass or steel casesd 7.62 rounds.