Yeah but that brightness becomes synergy with flat pads :P I've just rediscovered my SR325i with those and I really love the combo, it sounds much fuller and more balanced (less U-shaped, which is how I felt the SR325i was when coming from a HP-1); the spark is still there but tamed a little. I'll be leaving it this way for a while, I'm becoming more and more aware of how I want my Grados to sound.
Yes I do that quite often, take the grado sr80i comfy pads off and try it with the sr325i. Sounds good, less agressive and yes comfy, but everytime I do that I feel like I paid 200 extra pounds for a L-cush pad. I always have to say I don't have a high-end source.