I hope you can find a combination of spring and buffer for it. My 9mm AR is my favorite PCC out of all the ones I've owned (the HK USC with 9 inch barrel was pretty good

).
I did similar treatment with my G-21, running a heavier spring and my handloads had it cycling so smooth. I did a CQB course with TT and ran my 45 as my pistol, I don't think it slowed me down at all compared to my CZ SP-01 or my G-17. I have an even heavier spring for when I install the 10mm barrel
My experience with this little pcc has me wanting one, just hard to justify another $1000 toy when I already have the AR and a Vector.
My buddy with the FX-9 and I went head to head at 50 yards on the dueling tree with him on the FX-9 with a 1-4 and me with the Vector and an Aimpoint PRO. I don't think either rifle gave an advantage over the other. The plates were flying back and forth until we ran out of magazines, lol.