The gondola system is definitely less costs than the monorail but it won't move more people. The monorail system moves almost 7,000 per hour.
Has anyone estimated the time it will take to get from the IG to DHS including changing lines?
Without changing lines you're looking at about 10 minutes if you can travel 14 mph. Obviously turns will add a little bit of time and getting up to speed will take some time. So say 12 minutes, not counting switching