If it will read the same board the same a number of times in a row then it will probly work, (even if it is not reading "calibrated" correctly), as in a since your doing a comparison of the flooring to what is in the house all ready, (sub floor), it would be nice to check with a friend or a business that has a "know unit, with a reputation" to see if it is some what properly calibrated correctly. More for your own knowledge. or one could use the meter and then use the weigh and oven method to determine if the moisture meter is any where near, the link below will explain how one can do this,
http://www.lds4centres.com/NR/rdonlyres ... ontent.pdf
and
http://www.ces.purdue.edu/extmedia/FNR/FNR-156.html
I have worked in the Construction business for many years, and have also farmed for many years, and have bought on the cheap on some things, many times I have ended up wasting my money in an effort to save a few bucks, in that the cheap jsut did not deliver the accuracy or the repeatability or longevity desired. (one of the more memorable items was grain moisture meter I bought back about 30 years ago, wasted a $169 on that item.)
And yes the import market has improved much over the years, as much that is thought as American made is now many times imported or made out of the country, but normally there quality control is still better than a non branded similar product.