Yes, the mechs work in 1.3 just like always on planets.

However, in space only the Ronin Rho is fully effective because of how the boosters work on the rest of the mechs.
Sigmas will work until you stop the boosters, then mech needs to touch ground.
Rho/Pirate Rho might work ok, if you don't mind bouncing off the 'ceiling'.
Theta ...yeah, no.

I'm not sure yet if i want to tweak them to function better in zero-g, but the Modular Mech was built for space
besides, I've already started on XS Modules anyway :)