We had a fresh transfer using a 3BD if that helps? And we had a success! 9 month old girl! 
It wasn't a frozen though but we will have an FET this time round.
We have had really good quality time mind this time (all eggs between 5BB - 3AB) but I'm not really supportive of blastocyst gradings after everything I've read.
The embryologist just said to me that the grading is more around the following things:
The number - how far it's developed
The first letter - how far the actual baby cells are developing
The second lether - how the placenta and everything around it is developing.
Having listened spoken to a few and then done some research online it, the correlation between how far an embryo has developed and success rates doesn't seem to make much difference. It appears, the gradings can alter depending on clinics, embryologist etc.
The key thing is that they like to aim for a 3 and above for best chances but everything else seems irrelevant. There's still a lot of research ongoing to look into it.
Many people have had grade 1 blastocysts and it's not worked.
How this is positive! Fingers crossed for you xxx