yes, the iRig interface is pretty much useless crap. The issue with the iPad, iPhone, or iPod touch running the Amplitube stuff is that the mic-input impedance is too low for passive guitars and all these interfaces are developed for passive guitars. Our buffered Jerry guitars are much better suited for that kind of input. BUT, the iRig does some really bad stuff to the input level since it's passive and there's a serious loss of signal by the time it gets the impedance up and then into the iPhone, etc. These other products like the Apogee or others that use the dock port instead of the headphone/mic input are gonna be worlds better at getting a clean, quiet, and strong signal into Amplitube.
I don't believe that the better interfaces will improve the latency issue. That's in the software and iPhone processor itself, not the interfacing, as far as I understand it.
The Amplitube software itself does feel a bit slow or latent to me, just a bit. But I haven't heard it with a strong, good quality signal yet, only with the dreadful iRig which I quickly returned. So maybe if the tone improves, then the latency won't bother me as much. I can't imagine that Amplitube in an iPhone will ever even remotely touch Axe-FX, but hey, maybe a usable, mildly acceptable sound will come from it. It's a fun idea for sure. Uber compact and portable.
... and it's just like any other day that's ever been...