I ended up ordering two Vivitar 285's to accompany my SB600 with some Cactus v4's, but I didn't realize at first that the Cactus transmitter prevents the on camera flash from popping up, making it able to control the SB600. So now I've ordered two more receivers and will probably get one more low end flash just for kicks. I am actually kind of weary about the cactus triggers as I've been reading a lot of bad stuff about them now. Oh well, we'll see what I end up with.
Perhaps you should have searched a little more and researched a little longer. I know little about the V4 Cactus receivers, but I have a lot of experience with the V2s units. From the factory with fresh batteries they do an easy 30 feet, but the receiver raises the flash out of the center sweet spot and uses expensive unrechargeable batteries.
A *very* simple mod and both issues are settled. First thing to do is, of course, replace the batteries in the transmitter... this is a must. The second, is to solder a simple single strand of CAT5 wire of 12.39" in length. This 2 minute and 3 cent mod increases range from 30 feet to 350+ feet. I've measured my V2s units to 358 feet and ran out of room, and they were not even beginning to misfire.
Next, was to get the receivers off the light stand and attach a external AA battery holder. This way the flash sits on a hot shoe adapter and now uses rechargeable AA batteries.
The results were satisfaactory to say the least:
There are many people who do this mod and have issues ranging from a little to no increase in distance. When inquired how they did the mod, it was improperly done or the wrong length/kind of wire used in the transmitter. Of course results will be poor if the mod is done badly!
I've done several transmitter units (3 for myself and several more for others), and *all* perform near identically under the same circumstances.
My bog entry with detailed info on how to mod the V2s units:
http://jerryphpics.blogspot.com/2008/07/004-cactus-v2s-modifications.html