Until they decide to improve the SDM AF speed on the DA*300, then it’s questionable whether you’ll get any better keeper rate with it than with your present A*300, but that depends on whether your keeper rate concern lies with static or in-flight subjects. If you feel you need AF anyway, my thought is that the older F*300/4.5 would possibly serve you better, particularly as it’s more compact than the DA*300, whose AF is quiet, but not all that quick for moving subjects.
Although birds are not a big part of my repertoire, I was quite happy with the performance of the F*300 on my K-3, but I’m even happier with it on the K-3iii, because the larger viewfinder image makes framing (and manual focus) easier, and because of the improved AF subject recognition and AF speed (I think the in-body drive is also a bit quieter, but that’s just an impression). So, if you do decide to change lens and body, the saving on the F*300 over the DA*300 could go toward changing to the K-3iii.
Last edited by RobA_Oz; 09-06-2021 at 02:31 AM.