I built a tank (for some doctor's trolling motor for his canoe) out of brass years ago and I remember it was like welding aluminum except that it was very hard to see what was going on in the weld puddle. After welding, the welds were ground down and it cleaned up very nicely and held pressure no problem. It was kinda like very dirty aluminum. The fumes from welding brass are extremely toxic. For that reason alone, I would braze the coupling. That's just my opinion though.