The ability to set cross/upsell options at an item class level rather than just for individual items. Will allow organization to more efficiently manage cross/upsell options.
Official response
This is now available in SalesPad 5.6.7!
Relevant release notes:
UPDATED: CrossSell UpSell Maintenance: Item Classes can now be added as Root Items and CrossSell/UpSell items.
UPDATED: Sales Line Cross/UpSell Items: This plugin was updated to support CrossSell/UpSell definitions that utilize item classes. When the plugin runs, it will check for a CrossSell/UpSell definition for the sales line's item number as well as its item class, and display all applicable CrossSell/UpSell options. If any of the CrossSell/UpSell options is an Item Class, then all items of that class will be displayed.
Thank you for this idea! I have created an internal case for further review.