Keeping mine!!...........Some of the "go faster" guys will suggest taking them out cuz they run on the edge and over heat things but, in the same breath say/do "keep them in" if they run the engine in the "norms" not over heating. I run on the line only occasionally and had never over heated.
I tore my engine down few years back and after 23 yrs, had scuffing in a few holes. The infamous "plastic gear" teeth were still in perfect shape. I rebuilt the motor from the needle bearing's up, replaced the gear for general purposes just like I did with seals and such. I put every piece of the 23 year old oiler components under a microscope......literally.
What I believe through some moderate research, experience and evidence.......... The primary failure mode (there are outlier's) is that the "coupler" (high impact thermal plastic) melts down under stress of heat (over tach'ing, plugged water passageways, shot impellers, low lube, etc, etc) and seizes in its journal. The gear continues to try to rotate as of course the engine continues to run. The frozen/seized coupler then reflects too much load on the gears teeth via the drive gear and the gear's teeth sheer/strip!! It's my theory and I'm sticking to it...............
My experience/observation with every aspect of my entire pre-mix components (more limited then some here that have merc in their blood) I saw/have a system that is very robust and engineered actually quite well.
IME/O, If ya don't overheat/modify the engine and you don't allow oil hose/s to break/fail, you'll be perfectly fine for many years to come with it. It's run since 87 and it'll continue to run if you maintain it properly.
A lawyer told me once............"Ask 10 different lawyer's the same question and you'll get 10 different answers" Go figure..........
