Like most other things on guns, the quality of the design details and execution of them is more important than the design type.

I do recall something about a O/U gun, with monoblock construction, having a tube come out due to a bad solder joint. I think it was a newer Browning. I believe old Citori's were brazed or dovetailed barrels, breach to muzzle. The new 525 I have is monoblocked. I assume all the Citori line has gone this way for economical reasons.