We've calved out a few IVF's; probably 20 plus now. I can't really say I've seen a difference in BW's over the conventional ET's.
Had one last week and our embryologist was out the same day and he commented that the IVF's maybe don't have as much vigor at birth, but I've not noticed that either. Ours have got rolling well. We'll see how they do this coming week, with snow and much colder temps.