Cool to see somebody drop a good chunk of time. Good work.
Also, I skimmed most of the responses, but didnt see somebody really answer you point about your 10k being a lot "faster" than your marathon in terms of competitiveness. Generally the longer the race, the longer it takes to reach a given level. This is because it becomes more and more purely aerobic, which takes longer to develop. You might find if you ran a 5k that it was even more competitive than your 10k.