I would have to agree that over its history, Eureka did a lot of copying rather than innovating. But sometimes Eureka made the feature better - just like Japanese companies eventually improved upon American cars, televisions and even vacuum cleaners (Panasonic ended up making a better Dial-a-Matic).
One thing I believe Eureka proved: you really don't need beater bars to effectively agitate a carpet - rows of bristles can do the same thing as exhibited by Eureka's Disturbulator brush roll.
I think Eureka also eventually figured out a way to effectively grab all the suction from an upright's fan to use for attachment cleaning. First, it introduced a Bottom Plate to close off the suction from the brush roll windows, then it developed the pan converter which was also eventually adopted by Hoover. Airflow was never really great with both companies' "fan-first" uprights, but the pan-converter was the best way to grab whatever suction was produced.
I also think Eureka's attachments were better than Hoover's: when Hoover cheapened their upholstery nozzle by eliminating any bristles or rubber fingers, Eureka still offered one with a nice strip of bristles. Though Hoover's attachment system prevented tools from falling off, the locking mechanism did not allow the user to rotate the tool to a more comfortable or useful position. On the other other hand, Hoover introduced a much better bare floor nozzle with the Dimension canister which picks up dirt on both the back stroke and the front stroke (though I think Kenmore innovated that design).
Some other features Eureka offered to buyers before Hoover: an all plastic Tool Caddy, power nozzles for canisters, cord reels on uprights, top-fill upright bags, the Groom-a-Pet tool, easy-to-replace brush roll strips, front end upright height adjusters. Though other vac-makers innovated these features, Eureka copied them before Hoover.
