They'll work, the N designation is just changes in safety circuitry to comply with Japanese regulations. I suspect even the charger is the same in this case.
The specs listed at Adorama's product pages list them same capacity. I see no reason to buy the new batteries for older bodies, and the new ones are an extra $20.
When the "N" version of the LP-E4 came out, capacity increased from 2300maH to 2450maH.
Assuming the same ratio, I would expect the LP-E6N to have gone from 1800 to 1900maH...
The big difference is supposed to be new safety regulations concerning batteries.....
They'll work, the N designation is just changes in safety circuitry to comply with Japanese regulations. I suspect even the charger is the same in this case.
Aside from the gold-colored labeling, there are two fundamental differences to be aware of:
• Higher battery capacity
The new LP-E4N is rated at 2450 mAh, vs. 2300 mAh for the LP-E4 pack. In spite of this difference, it remains compatible with the EOS-1D Mark III, Mark IV, and the EOS-1Ds Mark III (as explained below)
• Compatible with new Japanese safety regulations for Lithium-Ion rechargeable batteries
Some minor changes have been made in the interest of safety, to conform with the latest laws in Japan for rechargeable Lithium-Ion battery packs