The more distance you put between your ear and the driver, the less bass and the more treble they'll have. You'll also have to increase the volume a little, but I don't think that'll matter with Grados. The high-end models are designed specifically for use with the jumbos. Probably if you put bowls on them, they'd be bassier and warmer than the lower models.
The only model that seems almost universally enjoyed with alternative pads is the RS1 and flats. And many like the HF2 with jumbos, but it's more balanced than the 225i.