D&D 5th Edition: Another Optional Initiative System

This is idea for an alternative initiative for 5th Edition and grew out of Mike Mearls' Greyhawk Initiative. For a previous attempt, see here.

Initiative goes from Highest to lowest roll and a d20 is replaced with the following system:

You roll initiative every round.

If you are casting a spell this round, roll a d6 + Dex Mod.

If you are making a weapon attack this round, roll 1d10 + Dex Mod.

If you have levels in the Fighter class roll 1d12 + Dex or Str Mod.

If you have levels in Rogue you add your Int Mod and your Dex Mod to the roll.

If you are making a ranged attack this round you have Advantage on Initiative, so you roll 2 of the appropriate dice and take the highest.

If you are moving this round you have Disadvantage on Initiative, so you roll 2 of the appropriate dice and take the lowest.

For simplicity, the DM can roll d8+ Number of enemies.

The highest number goes first.

Thoughts?