I'm not as experienced as some on here but I'm going with "It depends."
You have to consider factors like hauling angle, drag, rope going over and edge, etc. In my experience, when you're up there, you just do whatever type of hauling fits your scenario best.
Also, who really knows what their haulbag weight is exactly anyway. It's continually changing as you eat and drink (or drop things). Body weight changes too as you may have more rack on at certain times (or you get super dehydrated). Just go out and try it with various weight bags; you'll get the feel for when it works and when it won't.
Invalid question, although most space hauling scenarios will be a 1:1 haul. You could in theory space haul with 2:1, 3:1, 5:1, etc. point being is that your hauling ratio has nothing to do with space hauling. It is dependent on your pulley setup, not the weights of the climber(s) or bag(s). Your bag could weigh 1,000,000lbs or 20lbs, a 1:1 space haul is still 1:1 regardless of weights.