On day 1 i had horrible focusing issues, I chalk it up to inexperience at an airshow and poor camera configuration (C-AF+TR and not correct micro-focus adjustment) on top of technique. The 300 was set up pretty well from a prior micro-focus but I found it challenging to keep track of the fast moving jets. On day 2 was a bit easier. I decided to stick to one camera for most aircraft and seeing as I was happy with the 300 focal range I opted to pair the MC20 with the 40-150 for some flexibility, the los of aperture didn't bother me because I was planning to step up to get a larger focal plane anyway. I opted to keep C-AF with single small point, and did a quick and dirty on site micro-focus tune before the show by just taking a few shots of a distant object in the center focus point and then adjusting "default data" +/- until I was happy with the results in the viewfinder. I switched to my second body with the Pana-leica 100-400 that had a ND filter so i could slow down the shutter speed only for aircraft with spinny things. I also set up AF zone limits (50m-999.99m). This was a totally different experience to what I am used to, glad I went - it really pushed my skills to their limit.Those are fabulous images.
I used the 300 f4/EM1 MK2 combination last year. Your pictures are way sharper than mine.
Are you using C-AF or S-AF?