With romance readers in particular, if you take away their ability to resell/loan the books you've pretty much killed your market right there. No need to even discuss the built in light.
For 18 months I used my Librie pretty much daily and took it anywhere I went, including to and from China. I never bought even a single one of those clip on LED lights for it.
With e-ink you do get a superior reading experience. Very few romance novel readers ever get romance novels printed on clay coated paper that has been marked by a good quality press. It has been my experience, with the now older technology LIbrie panel, that e-ink works better in most locations than mass market printed books do. I expect even better form the Reader's newer generation e-ink panel.
In any case, the 500 year old technology has provided for us in the form of clip on LED lights. Those that feel they need one, can buy one. Those that feel they don't need one, don't have to get one.
Deal breaker or just rumbles from folks that have never experienced e-ink?
If I were Borders, I'd put together a romance bundle with a Borders eReader Bookstore Club Member Discount Card and a clip on LED backlight (with one of those super light weight AAA lithium e2 batteries in it) that has "Borders eReader Bookstore Club" printed all over it.