3:1 monsters and monster tracks (not disco)

[Quickleaf]

Considering a house rule for next 4e game I'm DMing...

The Rule

• Replace minions and standard monsters with a new enemy I have named "Monsters" in my creative brilliance. Monsters act as 3 in 1 standard monsters (or 2 for a particularly tough monster).
• Each individual monster is linked on the same "hit point track". All attacks against that monster type (e.g. kobold skirmishers) deal damage against this "track." Whenever the one-third (or one-half) marker on the “track” is reached a monster dies.
• In large groups of monsters there might be a group “bloodied” action, like a solo.

Why?

• The DM keeps track of information. Yah!
• Individual monsters go down faster and dish out more damage (since there's more of them attacking and easier for them to gain flanking).
• Monsters can often be taken down in one hit by a striker (unlike a standard) and “overkill” damage is useful (unlike a minion).
• Monsters avoid several pitfalls of minions: getting taken out by area effects in one fell swoop, missed attacks doing nothing, and critical hits or attacks dealing damage types they’re vulnerable are worthless.

Here's an example of what I'm thinking:

Kobold Skirmishers Hit Point Track
81
72 one dies
63 one dies
54 one dies
45 one dies
40 all kobolds shift 3 squares adjacent to same enemy and make a basic attack
36 one dies
27 one dies
18 one dies
9 one dies
0


The more I think about it the more I like it! Has anyone tried something like this before? How did it go? Can you forsee any problems with linking monster hit points as I'm suggesting?