It really isn't about "basement viewing" or 'attic viewing'. The issues start with the ambient light you have in your theater room. This, in part determines what screen type you choose. If you have, for example, a lot of window light you can't block out, you tend toward certain choices.
Then you ask yourself why you are going with a front projector - Is it for gaming? movies? 3D movies? sports? regular tv viewing? The answer to these questions tends to indicate the right projector.
Some guys have tried various ways to smooth out wavy screens (like ironing or hair dryer) - most without permanent success.
It's probably good that you picked the Optoma. It is DLP with a color wheel. Some people see a rainbow effect (to the point of being unwatchable) with color wheel machines, while others don't perceive them at all. If you do, at least you don't have a major investment in your projector and can upgrade sooner.
If your theater room is as dark as the inner chambers of the Carlsbad Caverns, and your walls aren't white, I would junk the screen in favor of a new white one. Some of the budget screens are a pretty good value. Then pay attention to the mounting distance and positioning of the projector. Should be a good experience.
Just my 2 cents