I am using 2x8GB 1600MHz RAM modules in this MacBook Pro. Works noticeably faster than the standard 1333MHz.
I used the 16GB config for nearly 2 years and never noticed overheating problems. The RAM was stable and the machine worked so well that at some point I wasn’t aware anymore of the modified configuration (now 2x8GB at 1600)!
I sold the machine in the end due Mac upgrade. RAM never failed on me, the system worked fine (no overheating as I applied new thermal paste way before the RAM upgrade (Arctic Silver, I recall?)).
Just in case I would get my hands on one of the 2011 MacBook Pro again, I would do the same thing: new thermal paste and RAM upgrade. After SSD upgrades (Bay 1 SATA 3 and Bay 2 SATA 2) this RAM change was hands down the best upgrade.