Will Blizzard ban you for using a macro mouse?

That'll get you banned

If you get caught, yes they will. It violates their terms of use and others have been banned in the past for using hardware that bypasses the limitations of the game. One click must perform only one action!

But I want an advantage!

Mice and keyboards that perform 1 action are considered legal by blizzard's terms of use. What this means is simple, you can have a mouse or keyboard with 100 keybinds and as long as their using valid, non-timed blizzard macros you can mash them to your heart's content.

These aren't the droids your looking for

Most of WoW is a testimony to your ability to play your character. Mastering a class and understanding every circumstance and nuance of every class and reacting accordingly is how you'll achieve mastery over the game. Just as the legal /castsequence macros are legal, you will always be better off handling your class like a champ. The game (especially in pvp!) quickly loses its black and white feel to dps/healing rotations and you're frequently required to make judgement calls. When do you pop your cooldowns? What happens if a proc occurs or a cooldown refreshes? When do you line of sight? As a gladiator my suggestion is always try and improve, your ability to react to every situation is simply non-programmable. Even a bad player with intuition will trump a timed macro (even if it wouldn't get you instantly banned)

Cause sources are awesome

This guy got banned for using a programmable keyboard and with the current threat to blizzard (bots) they have begun to have very low tolerance.

(wow forums post on programmable hardware) http://us.battle.net/wow/en/forum/topic/1965841764

(Example) http://www.infernix.net/wowban/

The rule of thumb is that if you can do something with an in-game macro or add-on, it's okay; if you can't, it's not. If you follow that rule, and err on the side of caution if there's ever any doubt, you should be fine.

In other words: yes, this will indeed get you banned if you're caught, because you're relying on casting multiple spells with a single keypress, which cannot be done using the in-game macro system.

Of course, even if this sort of stuff was allowed, or you (one way or another) manage to never get caught, it's generally not going to be possible to make such a macro anyway. Your latency is never constant, and any deviation in lag changes the time you have to wait before casting the next spell; cast too early, and the previous spell is still in effect; cast too late, and you're potentially wasting time.