This idea is to allow for greater energy/heat transfer and dissipation accross the surface. Your going to notice it most when you are under hard braking often (hard at work, trailering boat or play, well playing), as this is when the rotors will function at a kool temp. I dought that they are in any way inferior to the OEM rotors. The OEM rotors are subject to the same failer, for example when you get that shutter under braking. IMO its worth the money, I purchased mine from stop check, and they are cross drilled and slotted like 250 for the set. I would not change the calipers because then your going to need a larger rotor and your getting into a lot of dough for the big break kit. The OEM break lines are fine, unless you just want to replace them. The pads make a huge dif. to me as they reduced stoping distance and increased road feel and most of all cut the break dust way down. I would do it the way you have, then that way you can feel what your getting from each addition.

Happy motoring, and good luck