This is kind of similar to hero points from arcana unearthed. Let me copy a post from the AU impressions threadYou can do any one of the following things with a hero point:
1. Get a +d20 to any one rolled action.
2. If used on an attack roll that would normally hit you can do double damage or cause a called shot effect.
3. He can take a normal rounds actions outside of the initiative sequence
4. He can use it to gain a +1d20 luck bonus to his AC, saving throw or whatever. If he succeeds he takes no ill effect even if there normally would be a partial one.
5. If used to effect a roll where the character would normally die it instead causes him to suffer a great, debilitating effect.
6. The character can use a hero point to mkae something work in a way the rules do not normally allow (subject to DM interpretation).
It suggests that you be somewhat stingy with hero points. There is also a feat (Born Hero) that lets you start off with a single hero point and encourages the DM to be more generous with hero points for that character.
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3 means that you get a full round at any time, and don't lose your normal initiative check.
To add to that, 6 are things like tweaking a spell in a way not allowed by a metamagic feat, or basically applying a metamagic feat on the fly (like chaining a one target spell to the rest of the room).
Except for 5, it specifically says that you have to do it before the results are announced, a difference from you.
Either of these (yours or AU's) are fine, although I like the creative feel of the AU system better (especially the act out of order, and avoid dying features). That said, with either system, 3 seems a lot: unless you plan on running really tough, you're going to end up with very low player death, and adding significantly to the cinematic feel of the game (assuming that 3/level is roughly .5-1 per session). This can, of course, be your goal.
Edit: Not letting players know how many they have runs one problem: one of the usual goals of hero point system is to avoid a wacky character death, and if they don't know if they have one, you're going to get wacky character death. I would probably just let them know, but if you want to hide the info, then assign a random amount per level (d3+1 sounds nice) and then let them know when they're down to 1 hero point (such that they know to save it).
Edit^2: use 5 means: you don't die, but instead, you lose an eye, or some other equivalent sort of permanent loss (assuming the party doesn't have access to regeneration-type spells yet)
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