Babymaybe, welcome! This is wonderful news. As I am sure you know, overall success rates with donor eggs (assuming a young donor) are high -- definitely above 50% and as high as 80% per transfer in some clinics. I always want to soothe my nerves around this with stats and predictions too, but I think blastocyst grading is not the best tool for predicting outcomes. It's as much about stage of development as anything, and blasts at different stages of development can work well as long as they are within a general range. I think as long as you are in the "worth transferring" group, you are within the 50-80% chance of success window. This may be helpful: http://www.advancedf...ocystimages.htm
So overall, I would say it looks good! And if you're looking for stats to help, just know that donor stats are generally quite promising. Keep us posted!