First off, here's what the folks at Turbine have given Minstrels for instruments:
Serenade Defense Vital Cost Modifier: -15.0%
Serenade Utility Vital Cost Modifier: -10.0%
Serenade Offense Vital Cost Modifier: -10.0%
+15% Ballad Damage
+10% Ballad Power Cost
Threat Reduction During Combat
Basically the only two that people really use are the superior drum or the superior theorbo. Soloing, you throw on your drum . . . group, you throw on your theorbo. It's our way of toggling our abilities to some extent. Now to the outside observer +15% to damage is nothing to shirk about, but I have to tell you that it's not that big of a boost and the power cost is not that big of a power cost. As for the Theorbo, there's no real way of telling your threat in this game aside from mobs leaving their dance partners for you. Tell you what though, strap on your theorbo and add some lute strings of subtlety and you're not going to attract much attention if your tank is even halfway decent.
I just think that the potential for doing damage as a minstrel is kind of poor. Especially AoE. To get to an AoE spell, a minstrel has to cycle through 3 tiers of songs until they can get to an AoE blast, and even then . . . it's kind of pathetic. The legendary aoe blast (which is also a tier 4 anthem) actually does put out some pretty decent damage . . . the problem is the refresh on this thing is horrible; we're talking 15-20 minutes to refresh here.
I like the idea of functionality toggling. If I'm in a group with 3 healers, I think I'd like the ability to toggle my healing off and turn my damage on and turn it on big time. The introduction of these instruments and the threat reduction string for the instruments is a step in the right direction. I would encourage more of this and encourage the ability to damage dump AOEs more frequently. I don't want to have the best dps in the game . . . but I like the idea of trade-offs for the group or the solo'ers sake. If we have strings of subtlety, can we also get drum heads or drum sticks of amplifiction that would boost my damage and extra 15% and an extra 10% mana cost? Options = good.