Plastic guide rod?
Both my P09's have steel guide rods. Dull dark finish. Parkerized?? Melonite?? Some other surface treatment?? One is a 9MM the other a .40 S&W.
Don't know if they are different springs weights but my P07 and P09 recoil springs have the same number of coils in them (maybe why everyone says the P07's are hard to rack the slide on).
I understand the feelings about plastic guide rods. All of us have seen plastic break far to often. As far as I know, the P07's still have plastic guide rods. Old, or new, models.
Stronger ammo equals more recoil force therefore the need for a heavier recoil spring to reduce wear on the rest of the pistol.
My older P07 came with a "non-captured" recoil spring. Kind of aggravating during disassembly and reassembly. I changed that.