have you ever tested any of your plugins on a multivendor website, using dokan oror wc vvendors? if so did the fuck everything up?
We have a couple of people using WC Lovers/WCFM with Super Speedy Filters and Super Speedy Search.
Never any issues with Super Speedy Search, but Super Speedy Filters can be tricky to get the URL structure and template overrides correct.
Super Speedy Filters is coded to respect the author/vendor field and if you have the vendor filter from WCFM, then SSF will filter the other filters by that vendor (e.g only show product counts per category for this vendor)