I recalibrated my RS57 last weekend at 300 hours. My brightness was much too high (+10) as I absolutely wanted to calibrate so that I could see level 17 to flash. Now, I calibrated so 18 flashes, losing level 17 detail. my brightness is now at +5 and I like the picture even a lot more, deeper and more contrasty. Losing a small bit of shadow detail is well worth it in my case! Gamma went from 2.22 to 2.28.
Also, I used the CMS to recalibrate, using 75% of REC709 as my target. My 100% saturation deltaE got slightly worse, still remaining all below 2.2, but oh boy, did my 75% saturation deltaE improve! Red, in particular, looked perfect at 100% sat, but 75 and 50% were so bad, way undersaturated...Glad I did this!