Nobody can be in any doubt that SEN will have offered EZY a very attractive package in order to establish a base there. Which airport wouldn't in those circumstances?
As far as other new operators are concerned I doubt that they feel very inclined to offer anything above being 'competitive' and, indeed, I cannot see why they would act any differently. I know for a fact this to be the case in one instance so it probably applies in general. All airports know that in the current economic climate they have to be willing to be flexible with the aim of helping to get a route established, which is to both parties' long term advantage of course.