Few years ago a lot people would have said just the opposite:

Gnome was modern and broken in many ways, and KDE was stable but behind... Just proves why the competitio is good IMHO.

For the rest, I agree with you.

I wrote a 250 page tech book with Writer.

The publicer wanted all material from me in Word format. They sent all their templates in Word format as well.

It was few years ago, and I really did not want to use MS Word, because I've lost some stuff with weird Word crashes long time ago. Word must be a lot more stable these days, but back then it wasn't.

The tool is not the most important thing to worry about. The writing will take a lot time, I ended up writing to 3 am at night for several weeks. The last week before the final deadline was so bad, I slept one hour or so per night. At the morning of the deadline I slept from 6 am to 7 am, and saw a horrible dream in which rats were eating another rats. It was the worst nightmare of my life, which describes the state I was in.

It was a very good experience, I'm happy to have a book written by me in my bookself, and few thousand sold to others. Just prepare for the hours this will take! Tell your wife/girlfriend that for next 6 months you'll be extremely busy.