If it helps, my current work-around is to create vast arrays of constant combinators grouped by machine, with all the recipes each can make. It's laborious and error-prone, and produces just as many signals as all possible outputs that the recipe combinator creates. (currently 2,800 signals for >300 machines for Pyanadon)
That's the thing though, those 2800 signals don't have to all be squeezed into a single combinator :D Last time I checked, constant combinators with a huge number of signal slots like that got really slow...
I don't remember the numbers tho, and something may have changed since then to make it less painful, so I'll have to check either way.
The Transport Drones mod adds a recipe for every item and fluid in the game for the purpose of logistics. Each recipe require a drone as an ingredient, and asking a recipe combinator to list all the recipes that include a drone gives ~2800 signals as expected.
