I had plans for creating a similar mixed group, but I didn't because:
- The majority of those classes shares their item drops. Which means that the majority of the instance drops will go to waste (picture running a 10-man instance with the majority if the drops going to waste and all other items being needed by everyone).
- The cloth wearers are really vulnerable to melee damage
- There isn't much redundancy in such a group (only one class that can tank and only one that can heal)

I'd suggest getting classes that don't share item drops (the other issues are only real issues if you plan to pvp with this mixed group).