Just a word of caution... You don't need super high output pickups to sound "Metal"... Especially in a SSH arrangement, if your humbucker has way more output than the singles, a few of the following issues can occur:
1. Output difference: The higher output pickup will (obviously) be louder than the singles. So to tame the diff, you will have to keep the hot pickup away from the string (deeper into the body). This might reduce its ability to pick up overtones and pinch harmonics.
2. String Pull: High output pickups have stronger magnets. strong magnets offer resistance to the vibration of the string and hence the string vibration will decay quicker. This does not affect the strong pickup much because it can pick up much smaller vibrations and hence there will be very less diff in sustain that you notice. However, when you play on the weaker pickups, you may notice a loss in sustain.
3. Noise: Again obviously, the more powerful the pickup, the better is its ability to pick up noise from other interfering electronics like CRTs and certain types of lighting.
Extra high output is useful for people who depend on amp alone for gain and the gain of the amp is not sufficient. You can always use an overdrive/boost pedal to get the same effect. If you are using a pedal for distortion, just turn up the gain a bit more.
-- My current rig
Guitar: '98 MIJ Ibanez RG520 QS w EMG 81/60
Amp: Laney LC15R Tube, Fernandes 20W SS
Pedals: MI Audio Tube Zone Overdrive, Boss OD3, CS3, MT2, HM2, DS2, CE5, DD7, TU3, Beta Aivin DD2 Delay, Dunlop Crybaby 95Q, Stranger Vol Pedal, BBE SupaCharger
Others: Yamaha RBX 374 Bass, Yamaha MM-6 Synth, M-Audio Fast Track, Shure SM-57, Heet Sound E-Bow Plus
Wanted(pm if selling): EB VPJr/Boss FV500L,Ibanez w Original/Lo-Pro Edge