Well here's my 2¢, I bought a Tascam iM2x and attempted 4 recordings using it with a 4th generation iPod vs using my iphone4 (I didn't trust the calls or texts ruining the recording). The first attempt I recorded the entire show but about halfway through the recording became distorted. The 2nd effort was even worse, the thing just stopped about 30 mins into the show, this also happened on my 3rd & 4th attempts. I will say when it did record it was acceptable, not stellar, but listenable.
I finally tossed in the towel and bought some CA's, battery box, and a M10...I just wish I would have bought them sooner instead of going on the bare bones cheap road. I missed some great shows. The difference between my new small rig vs the idevice & Tascam is night and day. I Hope this helps your friend.
Also, I know this is a older thread, but I'm hoping my reply will still help someone contemplating a idevice mic setup.