Having read the post by Kiddforce about the balance changes in testing, I think that the rifts mode would be a good way to see the new changes in action. In my opinion, the PT mode is only good for testing endgame content and specific dungeons because of the way it is set up and the fact that gear is not reset every time they do a new one.
Using the RIFTS mode to test the new changes would be a good decision because then DECA would be able to get a better idea of how it affects player progression. The way I would implement it would be to have everyone start with a level 30 - 50 uncommon pet and an uncommon egg. I would do this because I think the lower heal levels are too weak to give a good idea of how the changes will effect gameplay and it would only last about a week so i want the players to get close to a max rare, where most of the balance issues with pet become apparent (perma helm, perma speedy, etc)
please let me know what you guys think, this is a perfect opportunity in my opinion