The accounting systems don't support packs very well, they vary in functionality but rarely have the pack sizes and minimum sales quantities that customers want. So in a number of projects we have added custom fields and javascript to manage some of this. It would be nice to build specific support for this into the product manager and ecommerce/CRM.
We now support this really well in the CRM. But, it would be great to have this on the eCommerce site too.