No, you cannot mix and match.
Also, NO other triggers will give you off camera TTL other than the Radio Poppers. That is their claim to fame. All triggers can work with TTL flashes... just not in TTL mode... lol
Asthetically, the PWs are the least offensive, and I feel that the radio poppers will look the ugliest with the Skyports somewhere in the middle.
However I am going to need some form of wireless triggers by June as I am seconding/ghosting in my 4th wedding and I was asked last night how my off-camera flash skills were. He also asked if I was interested in ghosting during the rehersal (just to get some extra practice), the morning preparations of the couple (day of wedding), and pre-ceremony as well as the standard wedding and reception scenarios.
I said yes without thinking about it. Looks like a great chance to see the whole enchilada in action... awesome!
I was sitting here thinking... I could get the PWs today for something over $800, but for an extra $150, I could have an 85mm F/1.4 Nikkor prime. Or I could get the Skyports and be a good way ahead in saving for the 85mm. More decisions to think about.