Does a 1.6 gallon toilet really flush better than a 10 gallon toilet?
As always, government regulations come on fast, with the expectation thqt industry will turn around and comply promptly.   Early on, the low-flow toilets were designed with one objective: save water to meet the looming regulations.  Flushing properly was left by the wayside in their rush to meet the low-flow requirements.  

As years went by, and low-flow became the norm, they got out the sharp pencil and really started iterating on the problem of getting them to flush well.  In the interceding years, they've done very good work on that.  I no longer notice flushing problems in modern low-flows.  They've worked the kinks out. 

It sounds like yours is an early "compliance model", I would shop for a new toilet.  Read the reviews.  

As for "better" that kind of engineering was never really done with the old toilets.  They just did the job with an overwhelming mass of water, "throwing water at the problem", which isn't really engineering, is it.