UltiMAK is great. Be sure to order the right version.

I use one on my NRA model. The scope on it is a Burris 2X7 pistol scope on Leupold QRW low rings.
To get the objective bell to clear the rail I had to remove a shallow valley  at the gas block area. The
bell sets down in that valley slightly so it clears the rail. Eye relief is great and cheek weld is too. I
don`t think I could have gotten the scope lower on the rifle any other way. Clearance on the other end
of the scope is about .040

I personally, dont get the use unless you have a model without scope scallops, if you prefer LER scopes, or if you just want the looks.  
They add weight.  
They get damn hot, its a piece of metal mounted to the gas block.  
They move your optic closer to muzzle, which makes rifle front heavy.  
Its better to have scope raised off the receiver, than low to the bore.  You get much better POA/ POI trajectory when it comes to 556/223
They look cool, but, IMO, the least practical application for the mini... except maybe that ATI stock.
What optic do you want to mount?

seems like the ultimak rail and its scout usage either makes sense to a shooter, or its just
a gimmick of some sort. I like it because of the eye relief and the low mounting on the gun.
I like the  scope closer to the bore.I like the area over the action clear.
It works for me with my 60 year old eyes. but I get it that
it just does not look right or fit the usage with some people.
Different strokes and all that. the term YMMV fits here well.

scruff

If your scope is over the receiver and you're getting dings from brass, you either have a pre-Ranch model rifle, or there's something fucky with your ejection and it needs looked at, because all of the Ranch Rifles (And the later NRA/Tactical ones too) had the ejection angle tuned specifically not to do that. Pre-Ranch rifles would surely beat a scope to death, however. That was part of the Ranch Rifle (187+) series upgrades from the earlier 180x series rifles.

I had a Milled DMS-1 in the stock Ruger rings on my Mini for about 1800 rounds, and it not once ever took a hit from ejecting brass.

Anyway, back to OP's question, while I didn't have an Ultimak on my Mini, I have handled several that have had them on there, and I'm a HUGE fan of them when they're combined with a MRDS sight. On the shorter NRA/Tac models, it doesn't mess the balance up much, although on a 18" Ranch you'll probably notice it a bit more. Keeping your forward-mounted optic light is a big thing here.

They are neat looking especially if you want a red dot.
But be careful if you have a newer model gun.

I put a Ultimak on an older gun and it was fairly easy.
Someone pointed out on another thread that newer guns have the gas block screws staked.
I checked out my 581 series and it's true.
One gunsmith reported that the original screws on a gun were staked on so well he had to drill them out.


That's more trouble than I want to go through.

Mine works great with a 30mm Ultradot Match.

I'm pretty sure that there is a scout rail and low mount red dot that will co-witness the factory sights on newer Mini's.

Anybody know which?

Mine is an older MIni and the ultimak rail and PA micro will co witness on it.

Mine worked great.  Used it to mount a Trijicon Reflex II.

Anyone like the AMEGA rail?

Also, does anyone have experience with both?
I'm looking to use one of them to mount a mini dot low enough to co-witness with the factory sights on my Tactical.

I've been happy with the Ultimak for many years. I will say ejection was a bit forward on my mini, and some scopes that were not set forward enough were hit with brass.

I think I will try the Ulimak and mount my Bushnell 125 on it and see if I can get me a witness.
Can I get a witness on Lord!