Ha yes,

good point. I haven't really tested this on products without attributes but I will make the fix.

The thing is at the moment, it uses the product name to figure out how to group products with attributes together as really there should be something like "Parent SKU" which would be all the sub-products. Perhaps an option on step.1 to disable it would help, but then why do you have attributes enabled if your not using them?

But these are the little things that make it not really suitable for the general public so I guess I won't be making it a contribution just yet.