Sorry about the disappointment, but unfortunately this is out of Line 6's control. Mobile In is a digtal audio device with an input, and no output. None of the iPod touch models support the use of such interfaces, and that includes the Apogee Jam and the Griffin GuitarConnect Pro (you can verify this on their websites). You're right that there are a number of other interfaces that do work with iPod touch, but they're all either analog inputs which have much lower quality, or else digital interfaces that include both audio in and audio out.
We do take care to clearly indicate which iDevice models each product works with, but again: Sorry for the misinderstanding.