The filesystem block size is 4096 so that's how much gets written every time a file with 4 bytes of content is overwritten and due to the overwrite, the same inode is being used every time. With two files, that results in a constant 4KB/s write on the sd card. Unless it does wear leveling internally (that appears to depend based on the make and model, somewhat hard to find exact details), such usage is sure to reduce the life of the card.

I was mainly looking to have (=wishlist) some easy way of polling the status of the unit from an external server within the same network. I'd then store the status with a timestamp in a database for later trend graphing (something the dashboard doesn't provide) and possible other automation. Having the option of polling for example something like http://futurebit.local/stats (+ some api key) would be a more usable approach instead of having to write some script to run on the unit mcu itself which would the push the sama data at some interval.