In the past, I've done a lot with p-TTL capable flash with the occasional shoot in full manual and supplemented by RF triggers. p-TTL being the pentax version of i-TTL and e-TTL that allows for high speed sync and has usually done well for me outdoors with the addition of exposure compensation to get a nice mixture of flash and ambient.
However, now with using Nikon gear, for various reasons, I've been thinking I want to use full manual mode with manual flash and RF triggers. There are some quirks, mostly with sync speeds, but I'm also expecting that I will have to work slower and most likely take more photos per person to get things right in quick hallway style cosplay photography. With that type of photography, it's polite not to waste peoples' time, so I'm trying to figure out the best possible methods.
The strobist brought up an issue with the D600 and sync speeds, as I understand his article
D600 = 1/200th max sync, 1/3rd stop less
D800 = 1/250th max sync
For a given situation outdoors in broad daylight,
The D600 would need some form of compensation to deal with a slower maximum flash sync speed.
*decrease the ISO (D600 does have ISO 50 which is nice):
both flash and ambient are affected, increase flash power to compensate
both flash and ambient are affected, increase flash power to compensate, larger depth of field
*Use ND filter:
both flash and ambient are affected, increase flash power to compensate, potential viewfinder and AF issues, but wider apertures can be used, potential quality reduction from the extra glass
ambient is affected, flash is more effective
I'm still leaning toward the D600, but trying to figure out if there is a large benefit with that 1/3 stop, especially in outdoor situations. One commenter on that article mentioned an effective 1.3 stops of flash power reduction, which seems like a lot when a Yongnuo 460-II can output around 5 or 6 total.
What I have now is two Yongnuo YN460-II, and 4 Yongnuo RF-603N triggers. That will allow me to have a trigger on each camera and two potential light sources. If I'm doing quick hallway cosplay photos, I'd probably only use one flash that can be triggered from both cameras as needed; using the simple hold the flash in one hand and the camera in the other (difficulties changing settings on the camera with one hand probably being an issue in practice, though I've done it before successfully).
Things like pocket wizards are out of the question. I could put the cash I had planned for a TTL capable flash toward the cost of a D800 instead of the D600, but that's still only a piece of the difference ($230 for a Sigma 610 DG Super). Getting the TTL flash has its benefits, but would limit my use back to on-camera flash most of the time.