MS does slow the sperm down, that is pretty well known around here. We have seen greater success with fresh MS sperm, in that we see higher fert rates with fresh than frozen MS sperm.
In my situation, and many others, the biggest factor on embie quality is the protocol you are on. It causes poor quality eggs, thus poor embies. I have no idea how your follie growth was during your stim cycle, but it would be worth asking about. In that, look at how your e2 levels rose, did you follies grow "congruently" , which means did you have a couple of lead follies, or did all the follies grow at the same rate at the same time?
I would ask those questions, and see what sort of modifications they would make on your next cycle before making a firm decision. For me, a different protocol, with a higher amount of FSH throughout the cycle was the key.
Good luck, and sorry for the BFN