Would you rather?

[boost]

Change weight without affecting size. Upsides of thick chicks with all the positions of skinny chicks.

[MadMojoMonkey]

Assuming all other structural properties are left unchanged, then being able to make something both strong and lightweight opens TONS of doors in engineering.

Getting to space with a model rocket scaled up in size still isn't happening.
Getting to space in a nearly massless Falcon Heavy is basically free.

It's a clear victory for changing mass, while maintaining size (and other structural and mechanical functions).