Would you improve a good SE ranked content?

[Zivush]

I am on the process of creating a new eBook based on the top ranked articles of my site.
The talent writer that I have hired for editing the eBook improved each and every article for the eBook.
These articles are really good (and that's why they're ranked so high), but after her changed and the writing style of her they became super-duper. My first thinking was let’s replace the old ones with the new ones. I am still hesitating.
Basically any good change is meant for the reader not for Search Engines, but I afraid SEs wouldn’t like it.
Will Google-robot like the idea? Could it be recognizable? Would you improve a good SE ranked content?

[tedster]

It's a judgment call. I probably would upgrade the articles as long as the titles remain the same. But there is no guarantee about Google's reaction. If the rewrites are truly better for the users, it "should" help and not hurt. I've been helping one site upgrade their content - it has helped with gradual, stepwise improvements over already good rankings.

[Zivush]

Thanks Tedser for your advice,
I am going to take your advice and upgrade gradually, see how it works before implementing widely.
Titles and subtitles are out of consideration (I won't touch them).