Yes, I am overclocking it to 2880 MHz (320 x 9) and it's "hammered" but not on all cores. I do have an aftermarket heat-sink on it.
Would you say a constant temperature in the low 50s Celsius is safe for long term operation?
That is under load? Heck, my OC'd Q9450 idles at temperatures around that, and that's been entirely stable for years. The only concern I would have is silicon deterioration due to OC'ing and high voltages over time, but even that shouldn't be too much of an issue.
Would you say in my case silicon deterioration due to OCing is going to be an issue?
Is low 50s your socket temp, or core temps? Socket temp is the one that SpeedFan calls 'CPU', directly above the core temps.
VID Voltage Range 0.8500V-1.500V
Voltage is the primary problem maker for chips, not temperature (as long as you stay below tjmax)