if you're considering the effects of flywheel lightening at the level Andy is talking about, the rotational inertia is reduced a bit, but that also impacts on crank bearing life as that inertia also reduces the sudden change in speed at the ends of each stroke. The change in speed in worn bearings can cause skidding of the roller elements and that in turn accelerates bearing wear.

Would you notice or know this? Probably not. I also think there is a low chance of this occurring as you are not trimming not much mass but the bearing boffins don't like this when I talk to them.