I have never shot a gun with sub gauge tubes in it and to be honest I never thought I would like it.
However...I just picked up a 16ga DHE 30" Damascus with 28 gauge Briley full length tubes in it. The barrels have a few dents and likely have low wall thickness(which I had measured today). Here is the gun:
https://www.gunbroker.com/item/975272749
I shot sporting clays today with the 28ga tubes and loved every second. The tubes add 6-8 ounces so you have a heavy field gun, but a great clays gun. I had skeet in the right barrel and mod in the left. I didn't miss much.
I am going to confirm wall thickness at the Southern, but will likely always shoot the original barrels with tubes and be on the lookout for another set of barrels.
I think the tubes add a whole new dimension. In fact I think I would shoot a few of my 10 gauge hammer guns more if they had 16ga tubes. It didn't take me long to become a fan...