EXR final images are HUUUUUUUGGGGGEEE - please add either png if u have to with alpha support or waaay better would be jpeg2000 which is an archival free format with many aspects to it . One exr image I just rendered is 147,000 kb the same one converted to jpeg2000 w alpha is 14,000 kb . To make a full movie with multiple layers would be many hard drives with EXR . I actually have to reconvert every output I do in after effects which is a total waste of time and takes longer then rendering out the movie . yes EXR may be may be a little better maybe - jpeg2000 is better than png as you can do an uncompressed version thats still really small.