The good news is the basic rules are pretty standard and for purposes of playing games in a competition format should prove sufficient most of the time--assuming the league continues to treat markers and potential marker violations as they have in the past.
The less than good news is no real progress has been made with respect to gun rules (and their enforcement) nor any substantive thought given to player classification.
Beginning with player classification the relevant section of the rules is 4.07 - 4.10. Basically a player retains the rank they played under last season unless their team won the NPPL divisional series in which case that roster is bumped up one division except for D1. [And pump, which is Open class play, though the rules are a little fuzzy on specifics.]
A "pro" player is defined as a player who has held a pro or semi-pro rank in either the NPPL or other national or international (series/league) within the last 10 years--though for practical purposes it really only goes back to 2003. [Because that is the year the NPPL 1.0 database was launched and the first season PSP info is available from APPA (not including the NXL.)]
The practical problems begin to arise because numerous contingencies aren't covered [except in the catch-all petition to get reclassified for $50 (4.08)] For example, since divisional teams are allowed to amend their rosters at will over the season what happens to players who may have made only one roster appearance to a series winning team? In the short term it is unlikely to matter much except that classifying players according to their own claims or current team roster isn't particularly rigorous and will probably not inhibit determined sandbagging. It also does I think a terrible disservice to past pro and semi-pro ranked players. Nor do the current rules provide a sufficient foundation for a comprehensive classification system.
Of more immediate impact are the gun rules (7.0 - 7.12) which are, far as I can tell, no real improvement over the old gun rules except there is an extra stage (or two) that allow for verbal warnings before the hammer (potentially) drops--but the process still remains largely arbitrary. And of course they've added the 15 bps cap. Unfortunately the cap is not accompanied by any explanation for how the league intends to enforce a 15 bps limit. There are plenty of penalty options but, as was the case before, their application is frequently subjective. In part because there is also no description(s) or procedure(s) for determining the legality or illegality of a given marker except use of a chronograph (checking velocity) or official's examination.
The problems begin in (7.01, 7.02) which contradict one another with regards ROF for a start though one assumes the cap supercedes other statements. Also in the same sections is the same old semi-auto, one trigger pull and release equals one shot definition that does not accurately describe the working of any electropneumatic marker yet is supposed to be the operating standard by which all competing markers are judged. (Wishing doesn't make it so.) 7.03 is an effort neutralize some of the simple and obvious ways marker performance can be altered. 7.04 - 7.05 relate to surrender and inspection of a suspect marker but these are purely procedural and penalties may still be handed out on the subjective determination of the inspecting referee. 7.06 restates velocity and ROF limitations and notes the relevant penalty sections. (Still nothing about how a ROF violation is to be determined.) Velocity is checked via chronograph as is the norm.
The next relevant section is Eliminations & Penalties. (22) And Suspensions, Disqualifications & Fines. (23) These 2 sections define the consequences assigned to various hot gun situations and gun "bounce" situations and the dreaded "illegal marker." There are no specific mentions ROF or other shot adding infractions or means of detection which leaves the league in essentially the enforcement position it has been in all along. With a ROF cap the league just added another rule it can't fairly enforce.