i would say you are missing some fast AF primes.
35mm/2.4 would be my suggestion, you can find one at $150 now. (i have one and it is still my fav)
also, with a tamron 28-75/2.8, you can get rid of your lens 1,3,4. unless you really need something wider than 28mm. f2.8 is just so great for walk around.
the 55-300mm you mention is great too, if you find yourself using long focal range often.
for me, i would switch your whole set except the M50/1.7
and get the tamron 17-50, DA 55-300, DA 35/2.4
it will be a big AF speed, aperture speed, and image quality upgrade to you.
plus you won't find yourself needing to upgrade to more expensive lens too soon in the near future.
another good thing is they are "budget" lens, it is possible to fund it if you can get rid of your current set.
well, it's just my personal thought, hope that helps