Hey. Well, I'm clearly biased as coco is my favorite substrate, so I'd tell you to go with coco. In my experience, coco is much less of a headache than a small DWC for comparable (or better)results if properly done. With only 1gl reservoir you'll face wild pH and ec swings and probably temp problems. If temps climb too high in the reservoir, dissolved oxygen will plummet and pythium may take hold of your roots, which is a serious PitA (been there).
1gl pots are plenty for coco, especially if they are fabric pots that will support pretty big plants. Coco is great but has a few setbacks itself. You'll have to be careful with overwatering when plants are young (been there)and salt buildup during flowering (been there also). Both are easy to solve though, wet/dry cycles when the plants are young and daily waterings in flowering stage with some dripclean/ataclean with a moderate ec all along the grow. Coco is much more forgiving than DWC when it comes to human error or sudden environmental change.
One last thing, you can automate coco waterings with dippers which will give you roughly as much control over your feedings as in DWC, or handwater if you prefer/have too.