I have been wondering that myself. Haven't found much in the way of data but here is a post that seems to indicate that the older Hercules Unique may be slightly less than the modern Alliant Unique. The opposite of what you were saying ? You may have to go back to the prior page to see what the poster is doing. The poster also indicates that he will be doing more testing to confirm his findings. I also remember he said something about the Alliant site reformulating Unique, which means it has changed.
Definitely do the load testing.