Ryan has confirmed my distrust of DE as a viable solution. On my last assignment, I actually uninstalled all the modules and replaced with Ubercart since it was a complete mess. Ubercart has really impressed me with how well it integrates in with Drupal. I also like the modular and extensible design.

I'm not sure how the database back-end can be customized, however. I'd really like a drill-down hierarchy like Manufacturers -> Models -> Products -> SKUs in the catalog. I like Lyle's manufacturer module. Can Ubercart be modified to support this kind of data structure?

Also, I'm confused as to how DE could get approved to support Google Checkout when it has all these problems and you guys have to wait for approval. It sounds like there is some politics involved. I sure wish Google would open their eyes and see how much brighter the future is for Ubercart.