The protector stone is only useful for the - 10 resist other stats are wasted, to be honest only place I would consider playing this would be in a 2os circlet or pelt so you still have 1 os to put what your missing like fhr and resist, but honestly - 10% DR won't change much vs most of the chars
For renewed sunder charms the sunder part of the charms don't work in pvp but the - 10 resist fhr life mana frw etc will work, but Remember that sunder also have a big downside with - 70 to - 90 to you own physical resist witch make it completely unplayable in pvp.
So my opinion if you got a 2os hat and already reach all your BP resistance and DR etc, getting a - 10 resist protector stone would definitely not be a waste but I wouldn't play it over other stats if your missing somewhere else.
Hope it helps
In this situation it would probably be better for a circlet rather than pelt then, since pelts have more damage than circs.
I wonder what the min-max difference is between a vita/life add or stats+res jewel.
Overall though, I think surviving isn't really a problem for Druids, so thats why the -10 had me wondering here.
I think I'll try a setup with the -10 in a branch, so I can easily swap between.