>>People get used to certain ways. Personally, I have strong 'metric background', but I got used to miles/pounds so backward conversion causes me some inconvenience, though I still dislike 5'7"-like sizes.
>>Customers should feel some benefits, even imaginative, to switch eagerly. I remember as 5 years ago when stock market went from british to metrics it was supported/adopted by retail customers because it promised real benefits.
>
>The real benefit would be in the grocery, where the prices of two competing products would finally be comparable by just mere eyeballing. Now if one is $0.33/oz and the other is $5.29/lb, how many people can multiply by 16 off the top of their heads?
>But if one is expressed per kilo and the other per 100g, the prices will even look the same, just the decimal point will shift one place.

People know that some product is always in pounds and another in ounces. They will feel lost looking at grams, or will demand the guy (head) who can divide by 28.