The thing is, the higher the coefficient value, the faster the zoom will feel in relation to a higher matched FOV, so that's why 177% feels faster than 133% when zooming. But of course a FOV is going to feel too slow if it is too low. This one situation should not determine which coefficient you use - if it's too slow then you probably should avoid using the weapon in that particular situation because you really don't need its extra magnification. Use it only if your target is far away enough.
Instead, you should pick a coefficient based on its advantages: 0%MM has better precision at the crosshair, 100%MM (177%) has better overall muscle memory (but worse precision at the crosshair), and everything else leans more towards precision or more towards better overall muscle memory. Though, keep in mind you can go above 100%MM... At this point, what you define as "100%" becomes arbitrary and dependent on your monitor size/sitting distance. We've actually been discussing this in another forum. It's probably a better idea to think in angles rather than distance on the screen due to the concept of perceived size, i.e. you want to match your sensitivity to a point on your monitor of the same visual angle instead of the same percentage of monitor distance.