Here's my personal set up and what I can do with it:
2-AB 800 and 2 SB800s
I have the 1 JRx transmitter, and 2 JRx receivers.
With the JRx transmitter on the camera, I can manually adjust the power settings on my ABs when the receivers are plugged in. If you want to be able to do the same with the SB800s you can either purchase the RP Cube, or you can DIY by splicing together this:
Nikon | AS-E900 Multi Flash Adapter | 25068 | B&H Photo Video
and a 1/8" stereo plug.
I have been able to use all four lights together with only two receivers by using optical slaves on either the ABs or the SBs, again all power output has to be manually adjusted.
If you want the high speed sync with the ABs, you have to get the PX transmitters and the JRx receivers.... if you want TTL, than it's PX trans and PX receive....
Here's a pic of the how I DIYed the RP Cube. The multi-flash adapter is the grey cord on the left, and the 1/8" stereo cord is the black cord on the right. You might want to double check everything to make sure that it's working before you seal it up. We used heat shrink tubing to make the connections solid. Looks a little funny but works like a charm!
