I can upgrade my Stag Arms Trinity 15 to a mid length gas system for free, it will just delay my order. Is the mid length gas system worth the wait?

Carbine vs Midlength - you'll get a softer shooting gun... and it's actually better for you.  Honestly it doesn't matter too much though - .223/5.56 doesn't recoil much.

https://www.guntweaks.com/mid-length-vs-carbine-gas-systems.html

Thanks for the info, by the article it sounds like a mid length is better all around, even if it isn’t by much

Mid length for sure!  The gun will function smoother and you will have the ability to make quicker follow up shots.

Midlength is supposedly softer, but, big whoop, it's an AR-15.  I can't really tell much difference between my midlength and carbine rifles.  What I do notice is the lack of realestate on a carbine length hand guard.  Midlength gives you more options for mounting stuff.

Do it! No competition shooter uses carbine length gas. If its good in the competition world it's good for you. Longer the better, you really only need 4" of dwell time. It also makes the rifle more accurate because the bolt is not unlocking losing gas and moving the rifle around while the bullet is still in the barrel. 

The AR is definitely the Honda Civic of the gun world...

Ideally, mid-length is the solution for dwell time differences between the carbine/14.5” barrel and a 16” barrel. But as you move the gas port away, you lessen the gas pressure. My .45 D/I upper has the port just in front of the barrel nut... but to allow something like 9mm to function in D/I, the pressure is high enough that chunks of the jacket are sent back into the bolt assembly (or so how Rudy from Macon Armory explained it to me).

Can deal with under/over pressure a multitude of ways. Adjustable gas block, and physically adjust the pressure going rearward. Buffers/springs/bolt carriers compensate for the pressure, by either slowing the bolt down or allowing it to move faster.

Mid-length might be better in some applications, but if the gun is over/under gassed, not going to make a difference if carbine or mid-length. Might be able to run a lighter buffer in mid-length...

Thanks for the input guys. I figure between the fact that its an upgrade I’m getting for free and all the feed back I’ve gotten, it’s worth waiting a little extra time

http://soldiersystems.net/2018/05/14/nswc-crane-carbine-mid-length-gas-system-testing-shows-increased-performance/

 

it’s worth about what you paid for it. (But you’re a taxpayer and NSWC Crane did the work soooo...)

Some of the comments are just....  jhc