I am too all in favor of IBL probes. This approach is very flexible, adjustable. It’s also very good in terms of performance. As mentioned, interpolation between prerendered cubemaps can make it possible to do day-night cycle. Full-realtime faux-ray-traced solutions are cool and all but I’ve yet to see one that doesn’t affect performance significantly. Lightmass is really-really awesome at what it does, but it certainly imposes limitations (rigid modularity, lack of option for real-time iteration on lighting even if the final result is to be baked, RAM issues with big open spaces, rendering times if you lack a render farm etc.). There is a reason why there are so many engines now which are in favor of dynamic approaches.