You speak of what you do not know. There are many fine Reformed Baptist missionaries. Grace Baptist Mission is a British missionary society with a fine record in many countries over many years. http://www.gbm.org.uk/Having said that, I'll believe that these young Calvinists are not out to take over our churches, but are ready to follow the Great Commission, when I see some of them come on out to the mission field and start churches. Where are the Reformed Baptist mission boards? There are none to my knowledge, though a google search will turn up a very few missionaries that say they are Reformed Baptist. Years ago there was a Reformed Baptist in Japan down on the island of Shikoku, but he's been gone for years.
Trevor and Teresa Johnson are American RB missionaries in deepest Papua. Their family blog is http://www.tandtfamily.blogspot.com/
Steve