FrSky's X6R receiver features 16 channels (6 normal PWM outputs and all 16 channels on the dedicated Sbus output). The X6R features the exciting new Smart Port and a traditional A2 port on the base of the receiver, simply remove the jumper and connect an FBVS for basic external voltage monitoring.
The X6R is smaller than the X8R, but still packs 16 channels and the new Smart Port that supports the new hubless digital sensors! Or, connect the new vario, and then connect the old hub to use existing analog sensors.
So how do you get full function from 16 channels on the X6R? FrSky has provided options! You can use the Sbus line to access all 16 channels. Using the FrSky Sbus Decoder, you can convert the digital Sbus signal to normal servo outputs. You can also connect Sbus servos directly to the Sbus line. 
But that isn't all the X8R can do. It can also work in "D8 Mode to work with the DHT, DJT, DFT and DHT-U transmitter modules. In this mode you have 8 channels. The neat trick is the Smart Port still works in D8 Mode!

Specification:
Dimension: 47.5 x 23 x 14mm
Weight: 15.4g with PCB antennas
Operating Voltage Range: 4-10V
Operating Current: 100mA @ 5V
Operating Range: > 1.5km
Firmware Upgradeable

Compatibility:
All 16 channels requires the FrSky Taranis, or the XJT module bound in D16 mode.
For 8 channels in D8 Mode you can use the FrSky Taranis or XJT, DJT, DFT, DHT and DHT-U modules.