We recently met a Doctor in our town who had an Elliptigo 11R bike and it fits fine on our rack with no modification.
If you wanted to carry two Elliptigo bikes, you would need to have one Add-on in between them because of the width of the base being larger than our width.
We may look into creating a customization to carry two Elliptigo bikes next to each other, but that will be some time off as we crank out higher demand items. :)
Some pics: