I would say that you're right with your observation concerning the P'sG in stock of Sweetwater and contemporary P'sG with their flat backs (like a Tele).
In terms of announcing model development I can assure you, that PRS is generally a silent operator.
I'll take the 513 as an example, which I'm very familiar with. None of the different changes have been announced up front, maybe they could be noticed in the spec list.
I'll pick out relevant changes:
The first production line PRS 513 Rosewood, 2004-07, consisted of serial 10-Top (flamed only by the way), Phase II tuners, 513 bird inlays, a 513 neck profile (on certain hang tags they wrote down Wide Fat), full rosewood neck, a 513 compensated nut, a PCB in the compartment.
Within this period they tweaked obviously the PCB to revision B (maybe around 2005).
2008 and 2009, model name PRS 513, they kept everything consistent, but: 10-Top (still flamed only) became now extra with costs) and the neck was made out of mahogany, the fretboard was made out of rosewood.
2010 is a special year with two limited runs: The PRS 513 25th Anniversary and the PRS 513 Swamp Ash. The Swamp Ash differed as follows: body material full Swamp Ash, neck material maple. Everything else remained untouched. Detail: Despite the nut: you could find models with the compesated 513 nut, aswell as with the US standard PRS nut.
The anniversary model itself differs by headstock logo, the new PRS bird design. The rest remained unchanged. Still flamed tops only (concerning 10-Top, too).
2011 is one special year for the model. It was named since then up to be disontiued in 2016 PRS 513 Maple Top (or abbreviated MT).
The overall composition of materials remained the same as being introduced in 2008.
But: Head stock logo: back to ordinary signature logo. The PCB became revision C. The birds were now the ordinary PRS birds. Tuners and nuts are one of the most intresting changes. There are models with standard nut and Phase III tuners, there are examples with 513 compensated nut and Phase II, but old nut and Phase III or new nut and Phase II are installed, too.
And talking about tops flamed and quilted were available (concerning 10-Top, too).
2012 models got the Phase III tuners and the standard nut as genuine parts.
Around 2014 the guitars received a matchingw rosewood headstock veneer, and this was the major modification, PCB became history (point-to-point soldered electrical connections).
2015 and 2016: Quilted maple tops for core models was no option in this years.
That said: Changes could be made by efficency or effectiveness reasons in the production, aswell for tonal reasons.
To advertise it is a little bit Rockefeller-esque. I think, this is primary not Paul's character.
