I've got the EBC TG Discs and Yellowstuff pads.
I'd pretty much say they're just about bedded in after 1000 miles. I took it easy on them for the first 300 miles or so, and then I did a few 60mph to 10mph heavy brake applications on a quiet road to start and bed the pads in properly. When you do this you smell an awful chemical burning smell from the pads, but it's meant to be like this and is called 'green fade' (it's burning off the red chemical coating you see on the pads before you install them).
They really do give some excellent braking over standard (but I do have uprated lines and fluid) and they take an absolute hammering compared with OEM with very little fade. They are more aimed at track users so they're definitely more durable than DS2500s (which for me didn't last long) but they take a lot more to bed them in to get their full potential.
Relic is spot on - the Yellowstuff pads really come alive with heat but are still better than OEM when cold and they still have plenty of bite. Where they excel is when you're on a spirited run, or trackday, and you only have to brush the brake pedal to get plenty of braking from them when hot. You can much more easily trail brake on a track into the corners with Yellowstuffs working on heat as you require less pressure on the pedal. You don't have to be as precise as you would with pads that really need pressure to get them to bite - just means you can keep a smidge on into a corner, keep the weight over the front wheels and reduce understeer a touch if you're going in too fast.
Personally, on the road there is virtually no difference to my eyes but I suspect the DS2500s may give you a better overall feel. To be honest, don't get too hung up on temperatures and which is better - they're both hugely better than OEM and will give you a much better set of brakes!