Most proper Competition gun are 18"-20" with rifle gas systems, which is the softest, most reliable system. So its the easiest one to modify and still have great reliability and still be smooth.
The lightened carrier has less reciprocating mass, The recoil impulse will be sharper but less duration since BCG cycles faster. This will causes is less disturbance of the sights. You get movement when the BCG hits the end of the extension, but very little when it closes. Now if you add an adjustable gas block, it reduces the velocity of the BCG, so the carrier just kisses the extension end, it makes it shoot even softer. This works great with rifle length gas systems as they run on lower pressure.
With Carbine systems, it runs on 2x the pressure and its just to much for a lightened carrier. so the idea is to slow everything down. This makes the recoil impulse longer but heavier and with a impact of BCG closing causing more sight movement. It seems soft, but its just drawn out over a longer time.
Once you set up everything correctly, making sure it is tuned as a system, then there is no issue with reliability, its when you make changes without regards for the rest of the system, thats when you run into issues
For my comp 18" rifle with a rifle length gas system, I run a lighten BCG.
On my 16" carbine length I don't, but do run an adjustable gas system.
For a HD, I would run a standard BCG if you have a correct sized gas port. But most are oversized and there need the extra weight of a FA BCG and Heavy buffer to slow everything down. Plus the extra weight will help close the bolt when things are dirty.