Not necessarily, integration into a traditional rig is very possible and viable, but it depends a lot on what kind of signal I/O and routing you can do.

The thing you want to avoid for the most part is doubling of preamp stages, and to a lesser extent, doubling of any stage of the rig.

With the Line In, you are only using the power amp and speaker of the Behringer, so you can use modelling for the preamp, EQ, and FX without doubling anything. Then you can also mess with the tone shaping that mic and cabinet models provide.

You have no FX loop, which is the ideal way to do this. Since the Line In doesnt work well, you must use the front input. It's going to be harder to get all around good sound becuase by doing that, you are doubling the preamps.

Set the global output mode to Combo Front to start. In this case I would also start with only Preamp models, the Bass and Treble on the Behringer on 5, and the Contour on 0. Using patches you like the sound of with the Line In, try to tweak the EQ on the Behringer to get as close to that as you can, without changing the settings on the POD. Do this at the highest volume you intend to play at.