I think it's very telling that Britain no longer uses the British system. Americans are all upset about the metric system because the packaging lobby has been very successful in getting the focus on how difficult conversion is. They made the confusion even worse by doing their so-called "soft conversion", where they kept the same sizes of containers and just put the metric equivalents on them. People looked at the easy-to-understand British unit beside the convoluted metric value (ie 1qt = 0.94635L). And it freaked people out. This fear has kept folks from realizaing that once we switched, the metric system is much easier to use, and there would be no need for conversion between the two. Just another example of the corporatocracy running the country.
The only real advantage is that I'd find myself ordering a kilogram of pastrami instead of a pound.