Drop spindles verses Droped A-Frames

[66farmer]

I'm rebuilding a 78 front end to install in my 66 so I need to order the rebuild parts and items to lower it. There is a shop in Portland Oregon called Charley's Drop Shop he talked to me about the advantages of the Dropped A-Frames. I have never lowered a rig before so I want to make the right call the first time. So is anyone using the Dropped A-Frames and is there advantages to it verses the drop spindles.
Thanks