This would be great! The expable items would also be an interesting thought. (although it would hurt so very much when my pet dies).
I had another idea that would open up a whole new world in developing for pet classes, but some thought would probably have to be put into the consequences. Add a new container to playerhouses called "Companion Totem". It would work just like a storage container where items could be removed/added with /cmd's but it would have a slot for each pet wearable slot. If an appropriate item (container could be made to not accept inappropriate items) like say a weapon was put into this container in the correct slot, a copy of it will be summoned to the characters pet upon typing a /cmd command. This would allow for using special bossdroppable pet-items for scaling pets up through the tiers. It would also lessen the pain felt when that superequipped pet of yours die.