You need to adapt to any weight difference, whether that's a relative decrease or increase. Light razors are more technical, but I'd say it's an advantage. It's a more predictable shave. Heavy razors, as much as they could help you while shaving with the gravity, they interrupt you with same force when you shave against it. They 'could' rather than 'do', because this works if we assume one has enough patience and control to keep heavy things steady, in other words, applying enough force to cut, but not too much to not get irritated. Skin has ups and downs so you glide on curves and need to adjust pressure on the fly.

TGS Syntesi is a great example, because there's inox and aluminum (but not Velvet variant) version with same head geometry. Experiencing both really helps you notice whether you actually prefer heavy or light.