Afternoon Craig,
I've not shot with anything else other than a Pentax, my hit rate has improved since switching to back button focus, I use Sigma lenses in the main, a 70 - 200 F2.8 and a 100 - 300 F4 mostly for military jets and a Pentax 150 - 450 for wildlife, its quite unwieldy for jets at over 500 mph, I'm comparing my successes with images I see from Canikon users around me plus a good friend shoots with a D500
I do honestly believe good technique gets around most of the shortcomings in Pentax AF, not always and I am frustrated at times particularly with jets or birds head on, a good stance, BBF, short sharp bursts on the trigger to keep the buffer open.
I use a K1 for a lot of things, for wildlife especially as it gives me the chance to crop in fairly big if necessary, a K3ii for the jets as the extra reach is useful, plus the shutter burst is quicker than the K1 but quite often I'll shoot 4 or 5 frames in succession then wait, shoot a few more whilst I'm hearing all around me, Canikon shooters shooting 30+ frames, all that extra processing !!.
Have a peep at my web site if you have time, the planes are on " The Aviator Gallery " and Wildlife is under a heading of the same name.
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