Training Totem Hit Analyzer

What for ?

See how your hit damage is calculated with all your passive skills, equipments, gems, etc.
How can we make sure some of the gems or enhancements are effective and how much ?
Is gems x or y active if I stuck it here or there ?
Is my passive skill xx useful for my xx strike with gems xx ?

The Idea:

A small arena with a training mannequin / punching ball / infinite life totem that the character can hit to see how much damage it takes, with detailed formula, mods and gems involved.
The training totem should have a slight armor and 10% elemental resistance, along with some evasion.
Premium training totem can be fully customized (resistances, aura, etc).

Implementation:

Either a solo arena, the kind of the one used in PvP, but with a training totem. On site shared stash welcome.
Or a backstage in town, shared with other players, in this case several totems would be useful to spread out the players. Each player only see his own hit analysis. The backstage is hidden from the main place of the town, but occasional sounds and lights would be seen through the folding screen.

Analysis could be displayed in the chat window, total hit points and target status (frozen,...), detailed hit points per damage type, computing details, items and gems are displayed with the usual mouse hover mechanism.
A better display, complete with a tree, would be great.

Similar but different suggestions:

Training Hall (chose the monster) http://www.pathofexile.com/forum/view-thread/485429
Training Grounds (build test area) http://www.pathofexile.com/forum/view-thread/36848
Training Dummy for DPS Testing http://www.pathofexile.com/forum/view-thread/193893

Yes, please add something like this GGG