Personally I think the Glow is much better than reading with a light attachment. I don't mind reading tablets at night, it doesn't bother my eyes. On the other hand I do get tired of the weight especially when reading in bed.
I can't comment on the return issue because I have not had a need to return my unit. I'm going on six months plus and no issues. I would be surprised however if Barnes & Noble was difficult to deal with on returns.
Other options include Paperwhite - I bought and returned one due to screen issues, large gray areas and blotchy. Or, there is the Kobo Glow which seems to be getting good reviews from owners. The issue with the Glow is when will it be available in the U.S. It appears independent book stores will be receiving them soon as in, next week, if they have not already received any. If you interested in that option I would check with any local independent book stores that maybe nearby.
Back to the Glow I can only repeat my experience has been very good. I don't think the contrast is as sharp as the Kobo unit or Paperwhite but again the Paperwhite seems to have a lot of screen issues.