Personally I'm open to the jockey being able to remove controls from whoever it mounts, though I think it's unusual that it's the only special infected who can stun a player indefinitely. Jockey, while fun, has always been susceptible to smart players who've been mounted quickly killing off the jockey player. Prior to the buff, I couldn't recall a time when Jockey had killed me at all. I think the stun should remain, however it should only last a few seconds (slightly less than the Hunter's or maybe as few as three given the Jockey has full control over its victims movement). The backstab debuff is too harsh a nerf and doesn't thematically fit the Jockey as it is right now, and a momentary stun would have the benefits of fitting to the source material as well as still giving players a chance to survive.
And to directly address the other point: I don't think that Jockey being better than Hunter makes the Hunter useless in comparison, especially given the random nature of Special Infected spawns. Hunter is harder to dodge, more aggressive, and can pin down its targets, whereas the Jockey is easier to see coming, has to find a window of opportunity to attack, and can either lead its target into certain death via mapkills or the horde. If the Jockey were to be altered similar to how I have suggested, I think these two would be on more even ground while still having their own personal strengths.