Cry some more...
The Huntsman always headshots at a range of closer than five feet, effectively removing any need for the sniper to pull out a melee weapon, giving some time for the attacker to attack.
One Huntsman arrow can take out 2/3 of a Level 3 Sentry's health.
One Huntsman arrow cripples pretty much any class to the point they have to run away, most likely to their resupply cabinet.
...Huntsman is OP. Don't say "Oh, but it's harder to aim, you have to predict where your target will be to hit them! It balances out!", because seriously, it's not that hard to get used to using it, and you don't have to aim it if your target is within five feet of you, you can aim at their foot and get a headshot.
Ambassador on the other hand- requires a learning curve and a buildup of skill to use effectively, not twenty minutes of play to adjust to the arrow's speed. Snipers tend to snipe from areas where no one is attacking them, where they can aim in peace. Spies using their Ambassador tend to be under attack, and trying to punch as many holes in their enemy as possible. Getting a headshot under pressure without a scope and with your bullet spread increasing... hard enough to achieve. I've been playing spy pretty constantly since the update, and since I've gotten my Ambassador, and I'm just starting to be able to pull off the occasional headshot kill while running backwards.
Huntsman snipers have been headshotting, bodyshotting, and the-air-beside-me-shotting since day one.
I don't know what hitbox the Huntsman uses, but it's fudged. Your head is a balloon, and your box extends a foot to each side of you. I've watched, on more than one occasion, on my screen, an arrow fly past me and into a wall, then a half second later, I'll die of a head or bodyshot.
Now I know you use the rifle, and I congratulate you on making a reasonable decision, playing sniper like a sniper instead of battle-insta-kill sniper, running to the front line and being able to instantly kill anyone at close range.