I really like the Eureka mechanic. It makes Civ VI much less linear than its predecessors where you'd always go the optimal route down the tech three. For that reason I wouldn't want to see Eurekas/Inspirations only giving a boost up to the first 50%, because it'd make them much less important, which would in turn make games more samey. I think the suggestion to have two different Eurekas/Inspirations for each tech/civic, that are chosen randomly at the start of the game, is a great idea. It builds on the strength of the Eureka mechanic by adding even more variation to the game without reducing their importance. I wouldn't say it falls under the category of a 'small change' though.