I think most of these ideas are decent but I'm not sure because the godawful manyshot change is too distracting.
First you are making bad assumptions when you say that DPS will stay the same but more consistent. Unless you're just cheesing a boss with too many HP from a safe spot, you're not going to have manyshot on 1/6 of the time and off 5/6 of the time. You're going to use it when you have a tough fight, and save it when you don't need it. You also don't spend every second of every quest firing your bow, sometimes you are running, sometimes have to help heal up the group, sometimes doing a puzzle, etc. When these situations are coming up, it is a great opportunity to use manyshot and then let the cooldown tick off afterwards, leading to manyshot being used during more than 1/6 of combat situations. Some builds actually use multiple weapons: bows when manyshot is ready, and throwing or 2wf when it's on cooldown. Obviously that whole build idea is now dead.
Archers are extra nerfed in heroics as well. Right now, the ranged power you get from manyshot scales with BAB so it's pretty low in heroics, but at least you always got 120 doubleshot. After the change, both stats scale with BAB so you'll get basically nothing at low levels. Arcane archer builds also rely on a lot of secondary effects. You can't just take away a ton of doubleshot from manyshot, give crit range/multiplier in return and expect things to stay the same. You've lost elemental imbue damage, which makes up a huge portion of damage in heroics, or you lose proc chances on paralyzing / instakill arrows and you're just not going to get that back from any crit modifiers. You have to consider how your changes affect more than just raw DPS.
But the worst part is archers are so much less interesting now. Rather than actually having to think about the best situations to use manyshot, just tape down your attack button and go do your laundry or something. Oh I guess you can also set up a macro to click your new manyshot button every 12 seconds too. It's one thing to mess with stats, when all that changes is numbers on a screen, but the manyshot change makes the game more mindless and boring too.