If anyone cares, I chose to go with the thruster suit and the 8x8 grid makes a big difference, also I don't need jetpack in the grid, the suit has the jetpack by default. Worth the somewhat lower protection imo.
Yes, the thruster suit is better than the power armor when you first unlock it. But you'll eventually get better power armor again so swapping starts to make sense later.
If I remember correctly the power armor get's better quickly while you need to wait a long time for a thruster suit upgrade.
At least I remember that my furthest (sadly abandoned) SE run had me carrying both suits and changing when in space. There are also modules to reduce your need for oxygen and improve your thruster speed. But things like lasers, shields etc are useless in space...