Looking at the new BP catalog, the New for 2015
Elite 7x Chirp with 83/200/455/800 (sonor only) $549.99.
Elite 7 Chirp 83/20/455/800 $699.99.

I believe the non-x unit has the HDI transducer, the x unit does not.

So, the new Elite 7 for 2015 adds chirp built in but, uses the same transducer as the older, non-chirp units.

I could be wrong?