Here is what TR has to say:
"Yes, Inventory & Simple Stock Levels DOES work with RC1 (I've tested it), with the known bug that products with text attributes break the code that prevents ordering more than you have in stock. (Text attributes were a feature added to Ubercart after the Inventory module was written, and Inventory has not been revised to take account of them.)"
Note the key point: only text attributes are a problem. If you have attributes with options, they should work just fine. It's only attributes without options where the user has to enter custom text that cause a problem.