I can't agree with this. Because Copper is Copper and the Coefficient of Friction for copper on steel will be a Constant no matter how it is applied. IMO the reason for the "Velocity Limit" is purely Structural, as in the Structural Strength of the Jacket. Push a soft lead bullet with a thin copper jacket too fast and the speed of Rotation will cause the bullet to fragment once it leaves the barrel. This the reason for the thickness of the jacket having a limiting factor on the produced Velocity. Plating can be a somewhat time consuming process and as a result in many cases a plated Jacket would be thinner than a jacket stamped from a nugget of copper. However Speer uses Elecro Plating to produce the Jackets on their Gold Dot bullets and those bullets are capable of some rather high velocities in some calibers. That plated jacket is also strong enough to keep the bullet in one piece during some pretty extreme impact events. In addition many Plated bullet suppliers are now offering "double plated" bullets rated for velocities up to 1500 fps. so that old 1200 fps velocity limit may in time go away.

Personally, I'm not a fan of maximum velocity loads, I work my loads up to produce the best accuracy and have found that point usually falls somewhere between the 50 and 80% points in the span between Min and Max. Because of this I really don't have any concerns about the produced velocity of my loads with the exception of the 357 Magnum. For 357 Magnum I use the excellent Hornady XTP and while a bit expensive have found it is a very accurate shooting bullet.