Being one of the early owners of high five ive had an early chance to look over his upgrades and I noticed something odd. Down the lower path you can get an upgrade that adds apples to his tertiary attack, but then the soul gem adds to that upgrade. Its odd to make you choose one path to access the soul gem.
On another note , straight out of the box his attacks seem rather potent. And the first few upgrades seem to add to it greatly. So any path should be sufficient even without the soul gem. Hes a very fun character overall.