I agree with you completely on the first part. I'm trying to find where in my original post I said anything about a processor should run at maximum temperature for extended lengths of time. A ~20C difference isn't going to effect lifespan of a processor, indeed it will more than likely be replaced before it fails.
Also 50C is a nice point to strive for, I agree. A few degree's isn't going to make any bit of difference, especially when the CPU is OC and at 100% load to boot. How often is a CPU really at 100% load? If a few degree's is cause for concern, kill the OC and run at stock speeds.