I agree with the basic consensus here - there's too many factors to be able to say one particular drop is better than another. The biggest of them being how high the particular vehicle is to begin with. If you've got a Type R, it's slightly lower to begin with.
But on I'm a firm believer in the fact that on a street car, suspension travel is "a good thing". If you drive on perfectly maintained, track quality roads at all times, there's obviously a lot less need for lots of travel. In that case, slam it as low as you can to drop your center of gravity.
For me, anything more than an inch lower on my stock prelude, I wouldn't be able to get out of my driveway. Well, I'd probably make it out, but my oil pan may not. And on the roads where I live, I typically scrape the bottom of the car a couple times a day at stock ride height. So obviously, on my car, a 2.25" race spring drop is hardly a good idea.
Doesn't ground control make a modified pillowball mount now? Something that adds another inch or so to your suspension travel?