I've been using Carbotech XP8s on the road for the past 6 months and they're absolutely fine as a daily pad. Only buy them though if you have a brand new disc, or it has been re-ground.
They work perfectly on track as you can see from my pic on the previous page, however when I run track tyres or if it is a really warm day, I can fade them with the increased heat. I doubt an S3 caliper/disc combo has the capability for the kind of braking power my Alcons have, so I can't see you ever getting close to fading them.
Pagid blues and VWR pads I'd equally choose, and more flexible in terms of being able to put them on used discs. DS2500s I'd avoid if you're tracking, although an excellent fast road pad. They have a habit of melting, leaving deposits all over the discs and causing vibration if you take them past the point of their heat capability. Other pads just glaze and simply need a cool down and re-bedding.
For my hot days on stickies I use Carbonne Lorraine RC6s. I do not recommend these for a road car, they'll smash your face in and ruin OEM discs in a week.