I'm not sure there are simple answers to your questions. Much depends on where you are located. In central Illinois for example, there is almmost always time to do something in the fall be it fertilizer with the 6000 or more strip tillage with the Pluribus.

As you go farther north of I-80 and especially north of I-90 there are many falls where you are lucky to get the crop out let alone do much of anything as far as fall fertilizer or tillage. Last year (2009) was an example of this even farther south.

In many cases Pluribus customers start out planning to use the Pluribus in the fall as they did their previous shank type strip till rig or other tillage.  Almost alwaysd after a few years they learn about the system and feel comfortable with and like the results of running the Pluribus in the spring often just a few hours or days ahead of the planter. Not just because of necessity but they like the logistics of pulling into a field untouched since the combine, do all their tillage, apply fertilizer and plant in one trip then move the crew to the next field. This is especially attractive to operations with lots of separate parcels of ground.

The Pluribus and the 6000 are both versatile machines. The Pluribus was new in 2009 so I can't answer that part of your question. They work well as a system.

As far as your question about the "benefits" of applying all P & K as dry along with all N as NH3 in one pass in the fall, that is a very location-specific thing. I am also not an agronomist so I will let you decide the benefits or drawbacks of any system. We just try to provide the tools to do what you want to do.

That all-in-one-pass system seems to be a popular in northern Kansas for one place. Here is a video from northern KS taken early last December just before freeze up of a Kansas grower applying all P & K + NH3 (anh3 high pressure system) in one pass with the 6000. You have to wait until the operator lifts and turns to even be able to tell their is ammonia being applied. 

Jim at Dawn