I love it. I picked up the scorpion the month they came out for dirt cheap with some horse trading and decided to SBR right away. It is an excellent SBR but the K config seals the deal especially if you are running a suppressor. It balances perfectly now with my honking F1 can. In the standard SBR config, it was a tad noise heavy for my liking. I didn't think of the M-LOK rails till after it was put together but amazon had those on prime which will be here Sunday.
If I had to do it all over again, I would have left it as a pistol with a nice brace and not dealt with the $200 infringement fee. My buddy picked one up with the tail hook and I would have gladly kept my $200 to use else where vs having the factory folder on it, but in the end, it's a sweet PDW rig. Can't wait for Magpul to release their line for the Scorpions.