With all these these cheap, plentiful, but weak brass frame guns on the market now, it makes good sense to plate and pin them. Then you can load up with full loads of powder and the gun will stay together.
Peening the frame with cylinder is not even a valid issue. If you want to make an omelette, you have to break a few eggs. What about the increased firepower, velocity, and performance of the full cylinder loads of powder, made possible by plating/pinning the brass frame ? It's well worth the increase in velocity and knockdown power, for a few little peen marks. With mods such as those, a brasser can be loaded with full cylinders and shoot all day long, just like a Remington 1858.
FWIW, the steel frames peen too. Any and every Colt open top peens the frame with the cylinder, by design. That's a red herring argument used as a distraction. Modern magnums stretch the topstrap eventually too, but you don't see Remington loading down their 357 and 44 magnum cartridges, because of it. What lame logic that would be. If the gun peens or stretches, then make the gun stronger- don't make the cartridge or powder load weaker.
I say it's a worthwhile mod, a few of those brass frames guns have come apart while I was shooting them, they can use all the help they can get. Looks ? What kind of person walks around trying to impress people with the looks of his gun. Who cares ? I don't remember seeing any wars won, or game killed, or smaller groups on targets, because a gun was good looking. That and 10 cents will buy you a cup of coffee, looks are window dressing, and subjective- all that glitters is not gold. Form should follow function, the plate on the "hot rod" gun says the structural weakness was recognized and addressed. I'm more impressed by the hand made plate fashioned in for strength, than by perfect bluing in that area on an otherwise weak gun. Like looking at a tunnel ram and 2-4's sticking out of a square hole cut in a Camaro hood- what kind of person complains about the hole- seems like selective bitching/nitpicking to me. The "looks" mindset is what gave us brass frames and "nickel" plated brass guns, for $250-$350 each new a few years back. The guys who bought them and were fooled by looks, got ripped off badly. Now they sell for $129 at Cabelas. That's what happens to a weak gun with good looks- devaluation and depreciation. The gun has to be structurally sound first.