Jason, it is better to use a 2 inch hose with a 2 inch bore wand. However they arent too readily availible. Using a 2 inch hose to an inch and a half bore wand is still better than just using an inch and a half hose.
Also 2 to 2 is much harder to move around if you are doing a lot of wanding.
For some floods I have used 2 and a half inch and rarely but 3 inch hoses too. They have incredible recovery but are like bricks to move around.
Best, Dave.
P.S. For what its worth I have always run 2 inch hose, from a portable or a truck mount married to an inch and a half bore wand via a whip line. It isnt as high a spec as everything 2 inch but the difference isnt worth noting. 4 hour dry or 5 or 6? No one cares, its still a clean carpet.