I have a capture card so I know exactly what my SNES consoles are outputting. Most 1-CHIPs are too bright but my US 1-CHIP-01 outputs very close to 255. Only green and blue are a bit too bright and is easily fixed by slightly lowering the gain on the OSSC. Its barely noticable on the display.
My PAL 1-CHIP-02 was way too bright, crushing the brightest 3-4 bars on the grayramp so I needed to mod that one with resistors. My PAL 3-CHIP outputs 235 at default gain so is much too dark.