i think they would look sweet. and you would probably notice some braking difference since the gases have somewhere to escape. you would probably see a greater improvement if you added some high performance brake pads to the rotors.
The benefit of having a vent for the outgassing is outweighed by the decreased mass of the rotor. Remember the brakes tranfer the kinetic energy of your vehicle into heat, and the mass of the rotors determine how much heat it can absorb and dissipate in a given amount of time. The drilled and slotted rotors have decreased mass, and in normal street driving, would not likely give you better braking. Where these performance rotors come into play is repeated heavy braking, such as during track events, where the pads are heated up to the point that they outgas.
Like the previous reply, you would get better performance with performance brake pads on normal rotors. I have Porterfield R4S carbon kevlar pads on my Murano and they have better fade free stopping power at the expense of more brake dust. If you do not like brake dust, stick with a performance ceramic pad such as those made by Akebono. Porterfields also require a stringent initial bedding in procedure, which may be impractical for the normal driver.
If you can believe it, the stock Nissan Murano pads are made by Hitachi. They are likely a ceramic formulation which is why they hardly dust at all.
You can get also get a firmer pedal feel by switching over to a performance synthetic brake fluid. Previously I had good results with Valvoline Synthetic Dot4 Brake Fluid on prior Nissans, and am currently using ATE SuperBlue in the Murano. The blue color of the ATE makes it very easy to do a full flush of the brake system (when blue fluid runs out of the caliper line, you know new fluid has run all the way through on that wheel).