Yes, having lived with m Volvo sail drive for 15 years with no troubles at all I am partial to them.
Perhaps if you had suffered some trouble, and some will no matter how reliable, you'd feel differently. Hard to think, with four of them, one won't get their attention.
The expensive parts reputation is not really warranted on routine items, such as filters, as you must know. However, venture into the less routine and it can be breathtaking. I just decided I would replace all the 12 yr old rubber hoses on my Volvo. Most are preformed, so can't be replaced with generic straight hose. Total cost for fresh and raw water was almost $900. If money is no object, I also had to wait a month for inventory.
My injectors must be cleaned every 400 hrs, which for us is about every 4-5 years. The engine begins to smoke if you delay. I wanted a spare set, so I wouldn't be forced to do this in the off season. Nearly $500 per injector, there are four. The turbocharger is $3k and non-serviceable. Asked me how I know that.
I will say, however, when running well, it runs much smoother and at lower RPMs per HP than its equivalent Yanmar.
But in this case my client wanted a simple marine diesel, not a common rail type. We knew the hp we needed and the task was to find four identical non common rail diesels. We found four Volvos. Simple as that. Client wants to minimize dependency on computer chips. This what custom design is all about.
Are all the equivalent Yanmars common rail? I agree with the point, if they are. Sailboats should have neither common rail nor turbos! Simpler the better.