I agree that discord is a good skill to have.
I'm surprised no one directly responded to the comment about possibly taking inscription over discord.
Inscription will give you a 10% boost to all spells that get their dmg buffed by eval int.
Discord debuffs all resists and skills of a target by 28% unless the target has bard difficulty of 160 in which case the effect is cut in half (14%)
10% boost to some of your spells will never surpass a 14/28% debuff ability, but that's not to say that discord is always the best bard skill to choose for your template.
I have a char that has GM music/peace alongside magery/necro and spellweaving. It would be foolish to sacrifice anything on that char's template to get discord, because that character does tons of dmg with spells because of the other synergies of the template. That character is designed for very specific environments where you encounter lots of small monsters (champ spawns).
If you're going after big game, discord is pretty much a must. Discord will make your damage spells AND your summons more effective against a target. Also, discord has great synergy with animal taming. Also, discord reduces bard difficulty, because part of the calculation for bard difficulty comes from the skill total of a monster.
Also, if you're considering doing inscription for spell damage, I would suggest taking spellweaving instead. You gain a lot of powerful abilities with spellweaving including a spell that can buff your SDI by as much as 60% (lvl 6 focus), which is considerably more than you get from inscription.