Meh, it's kind of hard to compare them on those points... both are dead quiet but the axe has more of a pop than the shocker. As for smoothness, I'd give the shocker an edge again, but the axe barely even moves in your hand. It's just a different feeling cycle. As for efficiency, that kind of depends on the rest of your shocker bolt set up. On the high end of the reported shocker eigenbolt numbers there's not a ton of difference, but in general the axe is more efficient. I think the axe is a great platform at really any price range.
Have a NDZ or Tech T axe bolt you'd like to trade for Boss bolt or sell? PM me!
Donations for an ultimate bolt test would be nice too.