Here's a start.

In the "English" gun trade, chopper lump barrels were generally on better made
guns (particulalry "BEST" english guns - ie Holland, Purdey etc.)

Chopper lump barrels cost more to make.

However I have owned Holland & Holland guns that had Dovetail lumps
but since all H&H guns prior to 1893 were made by W & C Scott
it doesn't surprise me.

When loking at guns, I generally rate Chopper lump barrels over Dovetail
in terms of value.

As to strength, failures - I have never heard of either failing but I'm sure
someone knows of one somewhere.

500 Nitro