Had a couple of questions on this new offering from iFly, so I went straight to the horse's mouth and want to share:
1) Is the transceiver single frequency? If so, what am I going to forfeit?  A)  Our  transceiver is on the 978 frequency. You will not be forfeiting any  services with this, and actually will gain many including anonymous  mode and ADS-B IN FIS-B and TIS-B information.
 2) I have mode A/C transponder now. Will I have to enter each squawk code twice? A) Our  RANGRs have an internal decoder that sniffs out existing transponder  information and duplicates it for ADS-B transmission. This is automatic  feature and you  will not have any dual entry. 
 If you have any additional questions, my direct line is below
Ashley Kelly,  Channel Sales Manager | FreeFlight Systems
860-377-5156 akelly@freeflightsystems.com
I hope this is helpful.