Recently encountered an otherwise well looked after Volvo 2000 series diesel with about 800 hours, reluctant to start and smoky when running. On disassembly for a rebuild the main problem was bores glazed - the verdict was ".... not run hard enough".
I regard 2800-3000 rpm as cruising on a Yanmar that peaks at 3400. Time will tell how long it lasts, but it's near the hours of the abovementioned Volvo already, and starts instantly and makes very little smoke.