The doors don't do a whole lot. I have it in a space where it wouldn't bother anyone having the extra light all the time. And since it's not painted a lot of light shines out, anyway. And yes, you can raise or lower the shelf. But despite the height between the lights and seedlings I never have any stretching. Right now I'm using the bottom space as storage. I used to have the taller sterilite cabinet rigged for the same thing. I could propagate in the bottom space and grow plants out a little in the top space. I think something like that would be great for an early start for fall and spring crops if the timing was just right and nothing got too big in the cabinet. Right now that old cabinet is out of commision and is being used for storage.
I like your cabinet. Lots of trays in there, very efficient use of floor space. Did you ever figure out the heating/cooling? If you use an aquarium you may be able to use it as a sort of heat sink in warm months and heating in cool months by putting in a small water pump and tubing running up one side and back into the aquarium.