I am an FFB and am getting married to a BT and am very proud of it.
I find BT (especially who became frum on their own) to be much more real and sincere and growing ppl than FFB who just went through the system and never had any real challenges.
To each their own but I hope you (health) are being facetious when you said BT should only marry BT. Every person has their bashert . One of the causes of the shidduch crisis is exactly what you are doing- excluding whole groups of ppl you or being picky like that without knowing who is for you.