Also, he's not stealthy, but that may have been intentional. So, if he spends all his time watching stuff, he should have good eyes, right

Then why is his precision lower than the other units?
The raider seems kind of weak. They sure pack a punch, but die alarmingly quickly. Maybe you could increase their stealth a bit to give them a better niche use.
Well, everything seems to be fairly well-priced (except Im still not sure about the Depth Diver) after playing a quick test game. Its difficult to say how much the clayformer, spirit walker, and burrower are really worth, what with their cool unusual abilities (very intriguing

), but I think youve done a good job.