I pulled this from a tire manufacturer..... you can interpret it as you like.
Too Much Pressure or Over Inflation
An over inflated tire is stiff and the ride will be rough. They don't give in much to bad road conditions and the size of its footprint in contact with the road is less than what the tire manufacturer intended when the tire was designed. If a vehicle's tires are overinflated by 5 psi, they could be more easily be damaged when running over that pothole you didn't see or the debris in the road you didn't see.
After starting out with both tires at equal pressure I have seen the inside tire 5 PSI higher than the outer tire in addition to it running hotter than the outside tire in certain driving conditions. Given the above explanation of a tire that is over-inflated by 5 PSI, it stands to reason that the two tires are not performing equally under the same loads and conditions. And if you put enough miles on under those conditions, the tire wear between the two tires will not be equal.
Since installing the Crossfire, both tires pressures are always equal and at the same temperatures. Bottom line is that is good enough for me.
And Bob makes a great point. Only having to aid air to one valve stem and getting to the exact same tire pressure in both tires is a real bonus.