Hi Blair,
Mine have probably needed cleaning and or replacement since I got the boat 11 years ago. I've been told at least one leaks when the engine is off and I get the overly rich mixture black smoke for a few seconds when I first start the engine after sitting for a week or so.
But, it starts quickly every time / runs fine with enough power for 7.0+ knots motoring top speed in the right conditions / and I have other priorities.
It used to be hard to start on the first crank of the weekend when I originally got the boat. I fixed the problem by using Diesel Kleen additive religiously. It not only helps keep the fuel system clean but also raises the cetane level which may explain why the engine went from being "A hard starter" to a few seconds of cranking when it's been sitting for over a week. Also, replacing the starter that the "experts" told me was fine (It wasn't) helped a bunch.
So, I leave it alone. Why? because the injectors are really hard to reach and may be stuck enough to cause damage if not removed by someone with real experience. There is no such person I know of on the lake, so I leave it alone. The initial smoke doesn't bother me.
-Francois