The main issue with this, is that there is no way to change the slab-state of a block while in Astronaut mode, thus if you had to break blocks to get into something (Or escape after docking or leaving a core) if you have been using slabs, these blocks will be placed down as slabs.

1. Spawn a ship core
2. acquire any hull, creative mode will do
3. Set the block into any slab mode,
4. Exit the core, and place down a hull block
5. Instead of being a full block as one would expect, its placed down as a Slab
6. spawn a new ship core, and place hull on it;(astro), these blocks too will be slabs

There is current no (clear?) way of changing it in astronaut mode, which, could be a problem for some