A few comments based on posts above:

Any slot, cross drill, etc. will potentially weaken the disk to some extent. Brembo has chamfered holes to counteract this. Brembo are one of the most respected rotor manufacturers going so I'd trust them. Mine have stopped the X5 for 15,000 miles now some of which has included a 2+ton trailer set up.

Slotted rotors are primarily designed for race application to de-gas the pads under extreme use. My research led me to believe these actually shave a slight surface off the pad on each pass to remove glazing. Perfect for track but reduced life on street.

Dimpled are a good compromise in that they de-gas but dont go drill the rotor

Stock rotors should be machinable - there is a minimum thickness stamped on them. Personally I'd never bother unless you scored one when it was fairly new.

Just my thoughts

i keep going back and forth and now I am thinking about just going with stock rotors again.

Being as I don't plan on racing the X, this leaves you with paying more $$$ for reduced life (i'm sure braking will be a little more agressive).

So basically do it for the looks/braggin rights or stick to the OEM solids unless you actually have a race application.

Brembo replacement rotors are very diff then the rotors they supply with their Big Brake Kits, night and day actually.
Personally, I don't think it worth the cost.
Good pads, SS lines, and quality brake fluid will have more benefit then the Brembo drilled replacement rotors IMO.

These rotors are not for track duty either.

Thanks... I think you are absolutely correct and this will be the route i go. Why do SS lines benfit you tho? They were included on my stoptech BBK kit for my 300ZX, tho i thought it was mostly just better quality and better aesthetics - how does it contribute to the brake performance?

There is no flex is SS lines. They will not only last a very long time, but will provide consistant brake pedal feel and feedback. If you add that with good pads and a quality brake fluid like I mentioned(ATE or Motul, I personally really like Motul RBF600) then you will be really happy with the outcome.

The interior design and cooling channels on the Brembo rotors that come on their BBKs is not the same as you get on the replacement ones, nor are they 2 piece design, so no real benefit.

I picked up my 2006 4.8IS last week. I have already ordered a set of new pads, SS lines and replaced the fluid to the one I mentioned. Im hoping to have the pads and lines in next week. I can provide info then on how much of an improvement it actually is.

SS lines also are less likely to burst or tear like rubber lines under heavy repetitive braking when the fluid reaches boiling point...stock BMW rotors are fine if you have...good pads, change brake fluid every year and use ss lines.

So I found a set (4) of SS lines for $115.00. Is that a good deal?

Thats not bad for a set of 4.
I just got some Stoptech ones, but I have to check my bill to see how much I paid for them.

EDIT,
My fronts were $67 and the rears were $75.

Any opinions on EBC Pads, I bought the "red stuff". After bedding them I can tell they are better than the OEM pads. And less dust.

http://www.ebcbrakes.com/redstuffinfo.html