I think I'll try the transistor option first, because the coil ones seem to be like a 2 position switch (NO-NC), while the solid state ones only opens and closes the circuit. With the solid ones, there's still a risk of having both the up and down positions of the motor connected at the same time (maybe a failure in the micro, maybe a wrong code...). If you look at the messages above, I ended up connecting the up wire to the NC connector, the down one to the NO (or viceversa), and the common to the line. Then I can control the on-off of that power line with a second relay.