CB200, EnLink and Rx switchover strategy

I am a bit confused regarding alternative Receiver Connections: I want to have maximum RF-link safety and therefore use two 2.4Rx and one R900. So I understand this can be solved in different ways:
1. You could Connect all three receivers into a CB200 (Rx1, Rx2 and Rx3). This became possible after CB200 sw v1.30. Switchover method is described in the v1.30 Release note allowing customization (150ms, 80ms and Mixing)
I Guess this is the best way if you use a CB,
but if you use a Powerbox, you could:
2. Use an Jeti EnLink2RS and combine one 2.4 Rx and the R900. The Enlink will then be connected to the PB RX2 (parallel).

But you can also
3. connect the R900 directly into a Rx with "ppm input/Sat" possibility (most have that), and connect this Rx to the PB RX2 (a serial connection). So what are de advantages with the EnLink, and over the Serial?

Does anyone know how switch over philosophy works with the EnLink2RS compared with the Rx Serial? The only reason I can see to use an EnLink would be if you use a RSat2, where there are no ppm input ports to Connect a R900 into. Right?