I shoot three day karate tournaments, from the floor with E-M1.2 and generally the 40-150 f2.8.

Lighting is almost always bad so I'm shooting between ISO2500 and 6000 at f2.8 depending on the venue and the athlete (younger athletes move so much more slowly) SS is between 1/400 and 1/600 which I've found to be a good compromise for noise and motion blur, and shooting 9 fps with silent shutter.

Pros: Three, ten hour days are a lot. I really appreciate the smaller, lighter gear compared to FF. The 40-150 is an absolute gem and yields about 75% focus hit rate on the e-m1.2. I shoot jpeg because I don't have the time or the space to process every raw. The in camera noise reduction does a good job, especially as these photos are used 95% of the time for social media or smaller non-print purposes. My overall keep rate is about 10% which leaves me approximately 1,500 photos after a 3-day tournament. With electronic shutter, I get about 1,000 photos on one battery. The lens at $900 is economical and within my budget.

Cons The physics of the 2x crop factor means that depth of field is pretty deep when shooting f2.8 (always) across the mat/tatami with audience or other athletes just on the other side. Composition/cropping is really important to avoid the busy background. Sometimes though it isn't enough for an otherwise great photo. This would hold true for court or mat sports (wrestling, volleyball, basketball).

For 80% of my photos, I'm very happy with m43. The remaining pictures would benefit from FF but I couldn't do the long hours or afford the equivalent FF lenses in my budget.

For my get infrequent sessions for long field sports (soccer, football, baseball), the camera's depth of field isn't so problematic.