I voted Uzi. Second choice would be Krink. I missed that last Uzi bus too and just could not love the Mac so I passed on all of it. Then I was going to do a Krink. Did not do it.
For me, I like to mark significant moments in my life with something I know I will keep. It may cost just $10 but it has meaning. This is a significant moment in your life, mark it with the thing that means most to you. If not, cover the next generation and put stuff aside for the grandkids.
Example, the day I walked in and bought those 4 RR lowers from you two years ago. They have meaning and a purpose to me, it was even better coming from a person I knew.
I have not seen all of your weapons, however what I have seen you pretty much have everything covered. The only gun purchase you would make would be purley for fun or your own personal enjoyment and no one on this board is going to sway that. You will get what you want in the end.
I've also seen some of your training videos and I know you have been to several classes. I know you also do the FNS and other shoots...during the year in a budget crunch for the said funds what's going to do more for you? A new gun or more ammo for what you have.
I think you enjoy shooting them all and you do shoot alot of your weapons that most people can only afford to run one or two platforms. This is why I would go with more ammo for you.
Maybe next year the play money comes back more and you can make those firearm purchases, the weapons are not going anywhere, but ammo always goes boom and you cant get it back when it leaves the barrel.
Serbu Super Shorty 12ga AOW - Nah. You've got buds that already have several. If you ever need one, its only a phone call away.
AKS-74U "Krinkov" 5.45 SBR build - Your 105 is already g2g.
High-End 5.56 carbine - I'd be very curious to see what you'd come up with in this department. But for you its kind of a "been there, done that" thing.
Select-fire UZI - I'd probably have to vote for this one. It sounds like you've already put a lot of thought and research into it. Another dip into the NFA world just seems natural for you.
Alternative - ammo/accessories for existing guns, and training - You're already one of the most trained-up dudes I know. Don't waste your more-limited "mad money" on these little things. You know you'll be slipping out "a box of ammo here, a box of ammo there" from work anyway. (not stealing, mind you-- not what I meant)
I just did the ACT DP101 and 201. So worth the money and it never hurts to get more proficent with what you have. besides im thinkin night vison and all sorts of other goodies will come in handy in the near future. Im hopeing to take the ACT rifle and shotgun classes soon.
Uzi's the way to go. I sold off a lot of my guns to get my Lightning Link, best decision I've made yet. My MG's come to the range every time, the other stuff rarely comes out of the safes. If you can find a way to make it happen, keep the M11 and sell some other stuff to get the Uzi, 2 MG's are always better than 1.