Hi,
If i don't make a mistake, dpx files are in 10 bits, so if your comp is in 16bits, it will be automaticly convert in 10 bits when you render your dpx.
there is no way i think to transform a 16bit comp into 10 bits, that's not the same thing, it is when you render your log/in dpx.
if there is an error, tell me what's happen, because i don't see well your problem. I am not familiar with flame, but i used 10 bits .cin in a movie and i didn't find any problem
Jazfx