The OSPi Python program you installed is still in active development by Dan Kimberling. It has also received a lot of updates since 2.0.1 that likely resolve a lot of the bugs you are experiencing. With that said, the Unified firmware is the official firmware that is written by Ray for the Arduino and recently all other platforms. The Unified firmware has some advantages such as per station watering times in programs, integrated weather adjustments, etc. The Python program is more flexible and offers a plugin system for quick expansion.
The tight loop bug is not fixed yet on the master code however the suggested fix of adding usleep(10000) seems to work great and am sure Ray will update this in the next version. Therefore, if you want to avoid high CPU usage and don’t want to edit code, stick with the Python version (maybe update it) for now.