It's personal preference, and our past experiences. Some good, some bad depending on who you ask.
All of the above described engine manufacturers have been making engines for decades.
I have not had an issue getting parts, but agree, they are probably more expensive than North American manufactures.
If Volvo had issues, I don't thing Eling would put them in their 40 and 50 ft, self righting passage makers. If I remember correctly, both there a E4 and E5 have a single Volvo D6, 370 hp engine, and no kicker. This boat is designed to go around the world.