Are 14.5" mid-length uppers as reliable as 16" mid-length uppers? I know that problems can arise from having a gas system that is too short for the barrel (ie, 16" with a carbine length gas system). However, I am curious if the opposite scenario would have a negative impact on reliability (ie, 14.5" with a mid-length gas system). I'm referencing this Spikes Tactical upper, FYI.

Also, does anyone know the weight of one of these?

14.5 midlength is the hot set-up right now. You'll be fine

This has been argued a thousand times here. There has been some, stress some, people who have reported short stroking while using Wolf steel cased ammo (known to be underpowered!). Shoot full power loads, and it'll be just fine.

I just built a DD 14.5 midlength with a battle comp, and on the first day hooting it, we were having short stroking issues using Tulammo.

Now, the only time it short stroked was when the stock was not firmly held into the shoulder and the recoil controlled.

Shooting brown bear there was no problems.

It had a standard carbine buffer I think.