your math is a bit off, since the %s are multiplied rather than added.
both spells start with ~85% spell damage (3/3.5) frost bolt then takes a 5% penalty by having a slow effect on it 0.85*0.95 = 0.8075 (80.75%). Then due to the new changes to imp frostbolt/fireball, you take another 10% off 0.8*0.9 = 0.72. To save space, in this post I allowed rounding error, however if you don't round at all you come up with 73.2857% for frostbolt. Lightning bolt doesn't take the -10% or the -5% penalties so it stays at 85.7143%
Further take each % and divide by talented cast time to get DPS%. Lightning bolt is 42.857% Frostbolt is 29.314% As can be seen 168 spell damage will add ~49 DPS to a frost mage and ~72 DPS for a Elem shaman. However you would still need to factor in % increases in damage and empowered frostbolt (for pure frost rather than arc/frost). But the faster cast time on LB DOES make it SCALE considerably better than frostbolt, and slight better than fireball, meaning you could make this argument about ANY piece of +spell damage gear.
However, who gets this all depends on your guild/group's loot rules, and whoever wins the roll/dkp/decision/etc. But yes, it does give slightly more to a shaman than a mage, although if the shaman is healing a certain % of the time, then it would not be put to use as often as it would in the hands of the mage.
both spells start with ~85% spell damage (3/3.5) frost bolt then takes a 5% penalty by having a slow effect on it 0.85*0.95 = 0.8075 (80.75%). Then due to the new changes to imp frostbolt/fireball, you take another 10% off 0.8*0.9 = 0.72. To save space, in this post I allowed rounding error, however if you don't round at all you come up with 73.2857% for frostbolt. Lightning bolt doesn't take the -10% or the -5% penalties so it stays at 85.7143%
Further take each % and divide by talented cast time to get DPS%. Lightning bolt is 42.857% Frostbolt is 29.314% As can be seen 168 spell damage will add ~49 DPS to a frost mage and ~72 DPS for a Elem shaman. However you would still need to factor in % increases in damage and empowered frostbolt (for pure frost rather than arc/frost). But the faster cast time on LB DOES make it SCALE considerably better than frostbolt, and slight better than fireball, meaning you could make this argument about ANY piece of +spell damage gear.
However, who gets this all depends on your guild/group's loot rules, and whoever wins the roll/dkp/decision/etc. But yes, it does give slightly more to a shaman than a mage, although if the shaman is healing a certain % of the time, then it would not be put to use as often as it would in the hands of the mage.
