Yeah, IWB probably sits just a bit lower and maybe just right for your P-01. My CZ's have optics so OWB works better.
My P-07 with optic and 15 round mag actually carries a bit easier for me. It's a Black Point Tactical OWB holster with 15 degree forward cant and at 2 o'clock the butt seems to sit nice and tight but comfy. Not sure if it's the holster or pistol or both. Maybe me.
But my SIG P365 in IWB kydex simply disappears. And on hot days with shorts in a Vedder Pocket Locker I sometimes forget it's even there.
I guess that's why there's so many choices in pistols and holsters. YMMV
I've never tried the aluminum thin grips on P-01 like OP has, but I would have to think they would help concealment.