I have thought about your idea. Even if we implemented the ability to change the style for check boxes so they could look like option buttons, this would be incomplete in a production control like iGrid. The other important thing we would need in this case is 'something' the developer could use to group several option buttons into one group - in which option buttons are checked/unchecked automatically when the user clicks them. I do understand that you can live only with the first part and implement the second part in code manually, but this is not acceptable for a good market product.
In any case, thank you for this excellent suggestion. I have remembered it and maybe we'll return to it in future updates of iGrid. If you need to implement this functionality in the current version of iGrid, I would recommend that you use special option button images to imitate option buttons in iGrid.