I was reading about this yesterday.... funnily enough.
The arguement was that grooved disks offer better braking, but wear pads faster. Drilled disks are prone to cracking around the hole under hard use. Flat disks are good all rounders.
You will see more of a change in performance by changing your pads to 'fast road' pads than changing disks. The only downside is that they kick off a lot of dust.
<span style='color:blue'>"So my BM makes me a flash bastard? Then I guess you're just keeping it real from the seat of your nova?"</span>
<span style='color:gray'>"...and the home of the brave..... is bravey 130bhp from a 7 litre engine? 100bhp/litre or don't bother building it!"</span>
<span style='color:red'>"Aaahh the UK; where every road is jammed, under construction, poorly maintained and unfairly policed, at least we don't get over-taxed for it........ HA HA HA!"</span>