Regarding the Marvel overprint debate, I feel it's actually helped my sales on Marvel books.  Although it's likely that most shops are now adapting to the print-to-order policy, I'm willing to bet there's a lot less unsold Marvels, percentage-wise, in most shops' backrooms than there used to be.  I'm more willing to stick my neck out on a product if I feel somewhat secure that it won't be easily available.  An important characteristic of a product's success in our stores is its availability.  I'll sell more of a product if there is little available at other shops and vice-versa.  A good deal of my ordering decisions depend on anticipating what other stores (specialty or mass-market) are likely to do.

I generally order extras on most top-tier Marvel titles, because I can consistently sell a lot in the after-market when they're sold out elsewhere.  The fact that my customers seem to really like reading the stuff doesn't hurt either.  The higher margins in the back-issue business allow me to carry and sample the lower margin stuff that I feel ambivelent about carrying.

Conversely, DC comics are rarely good back issue sellers, because they are generally available in overprinting, second printing, etc.  Until this situation changes, I will continue to order most DC titles with 4-week sell-through in mind, while ordering extras on most Marvels for back-issue sales.  It seems that DC must agree with the success of this approach.  DC seems to have eschewed overprinting on such recent hits as Fables, Y the Last Man and now, Batman #608.