Yes a middle set (well a middling set, we have more than 3). Last year this set at GCSE got Cs and a couple of Ds on higher.
I spent quite a bit of time in July looking through the new sample assessment materials (which were only released by the exam boards shortly before the end of term). They are hard. Up until then we didn't have any real idea of the level of expected difficulty because Ofqual were conducting an investigation, so this set started the GCSE course working through the higher tier.
The new Foundation covers content which makes it more like the old Intermediate Tier, but on top of that the questions are more challenging. The students are asked to give wordy answers criticising statements, justifying their answers and so on, so we need to go back and teach familiar content differently.
This class has got quite a few anxious girls in it. The higher tier paper is now so difficult that it may well cause them to fall apart.
These students are unprepared for the new style of paper. It may well be in a few years time when the changes are embedded lower down the school that this set might revert to higher, but for this year group and this class, I think coping with the new material on Foundation (they'll be doing trig, for example, and not asked in a straightforward way), and the new style of questions, they've got more than enough work to do over the next couple of years.
I do think that the grade boundaries will be through the floor first time around, and it may turn out that it's 'easy' to get a 4/5 on higher, but we just don't know. Like I said, with this class I don't want to risk it.