It's hard to tell if they would be a big upgrade without knowing what is causing your problems. I have Juicy 3's on my downhill bike and Elixir CR's on my all mountain bike. I like them both. The Elixirs have more adjustment capability, but they squeal at times, so I'm not sure if they will solve your noise problem.
As for the rubbing, if that is a bent rotor or out-of-adjustment problem, you could solve it without paying the $$ for the upgrade.
If the adapters and rotors are compatible between the Juicy 3's and Elixir's, you could use the 185 with the Elixirs. It's hard to say whether the 160 would be enough stopping power as everyone rides differently. I'm not sure whether the Elixirs have more stopping power than the Juicy 3's, as I haven't pushed their limits on my AM bike like I have the Juicy 3's on my downhill bike. The Juicy 3's don't have the most stopping power in the world.
Bottom line, I'm not sure they would be a BIG upgrade and I'm not sure that they would solve your problem. If the rubbing is an out-of-adjustment problem, it may get solved just because you put new brakes on and get them adjusted properly, but it might not be necessary to spend the $$ to do so.