Time for me to FINALLY weigh in on the Gravity Storm.
I'll start by saying that the Gravity Storm bridge model is now my go-to in EVERY humbucker-equipped guitar I own. I like it that much. I should also start by saying that I'm by no means a shredder, I play mostly ambient music these days with some late-'60s psychedelic/acid rock thrown in for good measure.
I started using this pickup after calling DiMarzio about a year ago and chatting with their techs. I had a '70s Japanese lawsuit LP that played like butter but I just couldn't get to agree with my amp. It had a Duncan '59/JB combo installed - the '59 sounded great but the JB was just too harsh and brittle, and in this guitar it only really did the Jimmy Page thing. I called up DiMarzio with the following requirements in a bridge pickup:
-uncompressed and dynamic
-smooth rolloff on the top end without getting muddy - fat on the top, clear on the bottom
-VERY high harmonic content
-able to cut through long signal chains
-less bite, more bloom to notes
Without hesitation, the tech recommended the Gravity Storm. I was obviously hesitant at first, especially given the fact that it's a Steve Vai pickup, but I have to say that DiMarzio really hit the nail on the head, save for maybe the last point (more on that later!).
Installing the pickup and setting my amp's EQs to flat made a remarkable difference. Whereas previously I was fighting with my amps and pedals to get the sound I wanted, I now had precisely what I was going for. A strong, present midrange. A fat top end that rolled off RIGHT before the sound got brittle. Extreme dynamics. A loud and clear tone, even with a ridiculously long effects chain. Oh yeah, and HARMONICS. There when I wanted them, not distracting when I didn't.
Thundering cloud of ice cream is, in my opinion, spot-on. This isn't your daddy's Evolution. There's lots of roar, burn, and sear to this pickup. It can and will drive in an extremely pleasant and musical manner. It isn't harsh, brittle, or screaming like I was expecting. The cocked-wah sound is mild at most; raising the pickup accentuates this.
Oh, and output. Yeah. This thing sits RIGHT where I want it to. Enough to really drive my tube amps and pedal distortions, but not so high that it won't play nice with the gain backed off. The way the pickup hits the amp and senses strings is really interesting too. It's less like a blade, and more like a sledgehammer. Sure, notes are immediate and hard. But they also evolve very musically; as a note fills out, more harmonics are present. I find this pickup is great at picking out different harmonics and making them distinguishable. In a mid-heavy guitar like a Les Paul, it's got some serious character. I use a cello bow a lot, and this thing is able to pick up on every nuance of my bowing and pick out all the harmonics I want (similar to Sigur Rós in many respects) without getting to harsh or biting on the top end. This is a very controllable pickup, but that doesn't mean it's polite
I've since also put it in another Les Paul (a Gibson LP Special from '02) and an '01 strat. In the Paul, it's got a similar effect, albeit with a hair more bite and growl; in the strat, it's a similar beast but a bit more present and clear. Now that I've finally found the pickup to end all pickups for me, it's really nice to be able to swap guitars and understand a pickup so well that it makes that element of my tone thoughtless. I'm super happy with this one, DiMarzio really knocked it out of the park with the Gravity Storm bridge.
I've currently got a new pickguard on order, as soon as that gets in the Gravity Storm neck will be going into my strat to turn it into an HSH monster; I'll report back with my findings once that happens.