Solo builds would still be at a disadvantage. It is impossible for them to compete over orbs, so even though it is theoretically just as easy for them to kill their opponent as always, they now have to worry about both being ignored as well. They have to focus on both restricting their opponent's creatures AND killing their opponent's mage without dying themselves. Solo mages are already short on actions, and this added stress of multitasking will really push them over their limits I think.
Still, removing the orb channeling bonus may be a good idea. I like the idea of getting some kind of reward for owning them, but it may end up with a run away leader issue. The person with control over more orbs, the one who is winning, is receiving the bigger boost to help them to win the game overall. So, while I like the idea thematically, it would make more sense mechanically for the orbs to give a penalty to the one who controls them. That way the losing mage has a small advantage to help catch up. This can also be thematic if done right, representing the stress of controlling such powerful relics. People may wonder why you would want to fight over objects that tax you, but that's a simple storytelling fix. Maybe they are incredibly helpful but it requires a large number of them (5) before you can activate them and receive the benefit. At which point, the game is simply declared over because they are so powerful you auto win.
This coming from someone who has never tried it before after reading an article regarding how extensively it's been playtested and enjoyed in it's current format. So, I feel kind of bad for criticizing it without trying it.
I love the idea that Sslaks can't hinder. I don't know if that really is part of the way they work or not. Using their affiliation as justification makes sense, but is questionable without neutral objects ever being mentioned before in the rules. Some people may consider anything that's not "friendly" to be their enemy. However it is explained though, I agree that they shouldn't hinder.
I don't really like the random orb placement. With 6 orbs in 12 zones, there's not really a lot of room for variation without clustering the orbs in some way which may result in an unfair layout. They are currently spaced roughly every other zone which seems like a good pattern to me.