My iphone 4s will do all the clean, amazing quality live audio capture you want. No setting of levels. It will also capture in 1080p - full HD. There are also hundreds of multitracking apps available. You can also run line in to it for far more controls. It also has a boatload of storage available. I've had over a thousand pics, mostly short videos, AND 2, 1.5 hour videos on the phone at the same time. Since the new iphone 5 has come out the 4s is now much cheaper. If you already have a cell phone then the iphone has that obvious use as well. My point is that you likely have to have a phone. Why not get one that does this important task as well as literally thousands of others. It is my computer. It is my video recorder, audio recorder, and video editing software. Most of the videos I've shot in the past year have been filmed, edited, and uploaded from the phone and I never went near a computer. It's my GPS, my main picture camera, my whole bible in every translation, my secretary, scheduler, T.V., email, level (literally, as in I set a gate post with it) etc etc etc. Since I bought it there are half a dozen chargers for home and car that i've eliminated. The batteries that I HAVEN'T had to buy since I began using it boggle the mind.
So is a digital micro recorder worth it? Not in my opinion. Just get an iphone. If you sign a 2 year contract, which I always do, it can be CHEAP!