The casting distance I get with 6lb Nano over anything else is pretty nutty. It's like night and day. Now if you're fishing east ditches, then casting distance really doesn't matter. But say the Geen and bigger tribs? It can make or break your day. Only thing I really dislike about Nano is the fact that ice in your guides will rip it to shreds.. Other then that, I don't see any downfalls. (Sans maybe the price). Too many positives to ignore. Also those hero hooksets are a lot of fun :)
I do spool up with Drennan Super Specialist or Fireline Crystal once the cold weather and ice get here, for a mono it's good stuff.