EDI-EWR is not much longer than EWR-SFO so the issues about single aisle are not really very different. I've done TATL twice now in the 757 in E+ and I've found it perfectly pleasant - far far better than the 747. However, what you should realise is that 757s fly much more slowly than the more usual equipment. In the case of EDI-EWR you won't notice but from LHR it's irritating to be overtaken by BA and VS while you are en route.