I just added the contirb today (latest version) and it works great, except for a couple of things.
Firstly, It adds two copies of an attribute. I have added a "Standard" attribute, and a "Coated" attribute, but the Coated attribute is added twice, and shows twice in the main view.
Secondly, When I added the coated attribute, I left the select box blank, and added the new price in the price box (ie 77 versus 70 for standard). When I go to checkout however when I have selected the coating option, the product price comes up as $-7. This is always the difference between the product price, and the price I linked with the attribute. It is thus, that I assume that if you dont selec + or -, the default is -?
Thanks,
Alex