I did a quick search and didn't find anyone mentioning this, but I could just be blind.. So I hope I'm not being a parrot here.
Anyway, Mage's Ballad really should have a sound effect play whenever it resets Bloodletter. Or some better way to notify the player. I'm only at lv 43 on my bard and don't exactly know if it gets better at later levels. (I have a feeling it won't.) But having to constantly look at my hotbar to see when Bloodletter's cd resets just feels wrong and bad.
In big dungeon pulls when I stack my dots to a point Bloodletter resets pretty much between every GCD, it isn't a problem. But every other time I'm almost dreading to use Mage's Ballad because it takes me out of the game world and forces me to watch the ability icon.
To me, not having a sound cue on a random proc feels like an oversight. For comparison's sake WHM gets a sound cue when a lily pops up. And they have a static cooldown.
EDIT: I've seen people suggesting Bloodletter/Rain of Death having charges (akin to Ruin IV), and I have to say I like the idea more and more each time. It would essentially achieve the same thing as a sound cue while removing, or the very least alleviating, the dropped dps for missing a proc.
The sound effect on MB procs is clearly a disliked idea because there are other frequent sound cues already in play at later levels. I completely understand this as a person who gets easily annoyed by certain frequent sounds/voices. Even with my recent experiences I could see it becoming ovearbearing since Bloodletter can pretty much proc between every GCD if enough DoTs are in play. Actually even before suggesting the sound cue, I was worried it could become too much. Glad to see it confirmed.
Also, the WHM comparison isn't really a good one since the Lily sound cue has a low frequency and it's the only one WHM's have.