Another quick update:
If at any point in threads or messages I ever referred to temperature in units of celsius it was a typo and was supposed to be fahrenheit.
For instance inside temps of the 6 channel NC502 or 8 channel NC252 when using an AC Infinity Aircom on the lowest setting is typically only 86-88F (not 86-88C as I may have mistyped responding to messages or post). Apologies as when I get out of lab I'm still stuck using metric sometimes.
With that said, I will at some point in the next batch of case manufacturing be adding small slot cutouts on the bottom plate for increased airflow. This will take a couple of months to make it into production, however.
For those with standard cases from me already, it isn't too big an issue for temps or even airflow. The case design is not sealed around the front/back panels or side rails so if using a top fan there is still places for air to be sucked in from. Not as freely as having cutouts. But for my own use case in my enclosed AV cabinet, it has not been an issue yet and I run 4ohm speakers off the 502's at reference level for movies.