It is good, but I prefer it without. With the suppressor you really need to use it like a regular shotgun because outside of R870 range you need 2 shots, which will usually get you killed if it's a face-to-face encounter.
With Long Barrel instead I can be more flexible. I can be 40ish-50ish feet away and get a OHKO, plus I can OHK headshot from a football field away.
Granted if you aim to get close anyway the suppressor is amazing, and the 2HK distance is still good. But I like to make my shots count so I want that long OHK.
But yeah, anyone who's trying the KSG should experiment with the suppressor. --- You are the universe Expressing itself as a human, for a little while