Insanity :10 hours per manastone, there's like 12 people on the list now

[Cen]

and then how many will actually be of any use to content or groups or raids?

There's only one class who can use the manastone for free at 0 cost to their health and can use it in Kunark / Velious at no mana cost as well to leave to a classic zone, and the majority of the users will not be that class ;p