Balanced translocation 6&21

My husband has the following balanced translocation: 46, xy, t(6;21) (p11.2, p 11.2)
After 3 years of infertility and a failed icsi we found that his poor sperm quality is related with the bt and the geneticist told us also that we have a 21,15% of having a child with unbalanced translocation....the options are having an icsi with dgp, do an cvs or amniocentese or sperm donor
we now have 2 blastocists freeze untested, after a egg retrieval of 20...what are the odds for being healthy?
Hope also to know more about this bt.
thanks