If you genuinely have space in your dash for two DIN-sized stereos, then you're fine with using a second head unit.

The empeg tuner is nice, but it is no more fancy than any other radio tuner. My tuner gets great reception (when it's installed correctly and there are no wiring problems), and I particularly like the fact that I use only my empeg in the dash so it looks nice. I also like the fact that I have completely rid myself of carrying CDs in the car. So for me, having the Empeg as my only stereo is the perfect solution, and therefore the tuner module is indespensible to me.

But if you're already set on having a second head unit, then you can safely skip on the tuner module.