Hi,
I'm currently on my year abroad in France but will be coming back to Sheffield for my final year in September. I lived in Howden in Endcliffe in both my first and second years at Sheffield. Oddly enough, I actually sent off my application to return to Endcliffe for my final year this morning and I've chosen to go into Birchen.
I lived with first years again in my second year and while I enjoyed it, I think I'd prefer to be with other like-minded returner students in my final year, just given all the pressures of the last year etc. It was a laugh living with first years again in my second year but I think the slight difference in priorities between first years and final years might make living together awkward. Plus, Birchen's in a much quieter area of Endcliffe (up round Stepho's bar) which will definitely be a plus in final year given that it can and did get quite noisy around The Edge and the centre of Endcliffe (especially at night).
As far as I can tell the Birchen flats are exactly the same as the rest of the new Endcliffe residences (ensuite, shared kitchen, identical rooms etc).
So while I can't comment on what exactly Birchen's like having not yet lived there myself, I'll be there come September!