I suppose it doesn't really matter what the discount % is as long as the final price you pay is ok.
When I first started looking for discs and pads with ECP and carparts4less they were both up around £270.
I wasn't in a hurry to get them and kept watching the prices. I eventually got them from ECP for around £230.
Only thing I don't like about ECP is if its not in stock you cannot collect from a store and it is couriered to you.
You don't know when it is going to turn up so don't know where to have them sent, and mine were sent to me in 3 different deliveries.
I would have been happy to collect them from the nearest store a week or two after ordering, it would have been easier.