A good card will last years. Being prudent, replace it every year or so.How worried should I be in practice about the MicroSD cards "wearing out" with XiVO in 24/7
As an example, take a low end write cycle value of 5K (most cards are 10K+++). The ENTIRE card should be able to rewritten 5000 times. Now logs don't fill entire cards, the same "disk sectors" can be rewritten over and over, so in theory a particular spot on the card could wear out. To prevent this cards use wear leveling which spreads the writes around on the card, and even move a failing blocks to a new location.
Cards that fail in the near to mid term under pbx type work loads are not worn out due to write cycles. Something else has blown them up.
Yes. I log to ram to eliminate unnecessary writes. The best option for Raspbian if you want the logs to survive a (deliberate) reboot is the fs2ram package. A random power outage or reboot could result in current logs being lost, but that is the risk for any ram based logging.P.S. Googling SD card wear issues I see references to using something called "tmpfs" on Linux-based systems to extend life of SD cards ... would this be a feasible approach for XiVO on Pi?