Some significant player-visible changes are coming in PNC:R 1.14.4+. A lot (not all) of this is based on MineMaarten's document here: https://github.com/TeamPneumatic/pnc-repressurized/blob/redesign/documentation/TechTreeRemarksAndProposal.md (note that some of the points in that doc have already made it into the 1.12.2 release).
1.14.4 and 1.15.2 have releases on Curseforge now, and an alpha for 1.16.1 has just been uploaded. All new development will happen on 1.16.1, but 1.15.2 will be getting critical fixes and easy-backport stuff for a while. But no further development for 1.14.4, sorry. 1.16.1 is where it's at now.
Dev builds are available from https://jenkins.k-4u.nl/job/PneumaticCraft-Repressurized-1.15/ and https://jenkins.k-4u.nl/job/PneumaticCraft-Repressurized-1.16/. Jenkins builds should not considered stable, so seriously: don't include them in any modpack. However, they're there to play with and even provide feedback on if you're feel