i had the same issue with my wrx. i managed to warp the rotors and fad out the pads (thats the sound you're getting). the factory brakes are crap and i knew that from the very begining so there was no way i would stay with stock. i picked up some slotted rotors from MRT and some non-organic performance pads and the brakes are better then new. there is slightly less fadding (still need to change the fluid) and the feel is a bit better. the only thing i have noticed is that they are a little bit more noisy. i guess that just comes with the slotts. that's what i recomend you do.

 

i warped the rotors which made the jerk when i aplied the break. i also had the metal grindind sound you metioned. thats the cars way of telling you that the pads are worn and need to be replaced. i never went back to the dealer because i knew that if they fixed the breaks i would still be stuck with crappy oem parts. if you know anything at all about cars and how to use a wrench then you can do the work yourself. real easy and quick.