At idle the clutch is not engaged so the trans or drivetrain will not be in motion. There would be no difference to the engine or any problems as idle rpm is just that , idle. I have not experienced any belt issues on my machine. You would just have to figure in the fact when the trans is not in park the vehicle could roll away or the throttle could be applied for some reason when unattended. This could turn out to be bad or end up on You Tube as a fail video!!!
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