Mixing in different search algorithms is a great way to add life and variety to the ecosystem. I would think there are some technical hurdles (page load speed, removing duplicates) but definitely worth pursuing. It would probably benefit other marketplaces as well.
However, we may be a bit naive thinking most buyers use the default "Best Match" search sorting. Maybe 90% go for "Best Sellers" in the drop down menu regardless.
Another method would be to simply "cap" the sales weight variable, displaying only ">100" or so, and let other variables like upload date take precedence in the best seller group. Buyers would still feel they get "the best items", only not just "the three best items" at the top of search results. At least that would distribute conversions a bit more evenly where it matters the most in regards to PF and dinosaur regeneration.