Yuh Woon-hyung had a great deal of potential, but he was limited by being based in Seoul, not Pyongyang. In a completely Soviet-occupied Korea, he would be much more likely to be able to rally moderate leftists along with other leaders such as Cho Man-shik and Kim Gu.
One scenario that I could see happening is that Kim Il-Sung might end up being given the position of Defense Minister as was the original Soviet intention. He might even up siezing power in the end anyway, but a stronger moderate wing means his personality cult might be less well-established. This could mean that North Korea might be persuaded to deStalinize during Kruschev's reign.
Without the personality cult of Kim Il-Sung, the likelihood of a peaceful resolution to the Korean division is much higher than in OTL. Perhaps a figure like Hwang Jang-yop could rise to power and institute capitalist reforms following the Chinese model.