I recently bought a Cactus v4 wireless radio flash trigger and as I was researching the product online I found very little reliable information. (I am not going to provide specifications or any links to the product, as this is not an advertisement. Google it) So, if anyone are considering getting into wireless flash, here's what I found:
Test gear: one Cactus v4 transmitter, two receivers, Olympus OM-1n, Ricoh 500G, Agfa APX100 film, Canon powershot G2 (It's not a digicam!! I prefer to think of it as a "visual lightmeter") and a Nikon D40 (okay, that's a digicam... guilty) National PE-3066G flash and Sunpak 3075G flash.
Easily the cheapest option. I did however have to pay a customs fee that was more than half the price of the product. Not a tax but a fee for customs opening the package and declaring that the value was to low for import tax. (stupid, I know)
Also very cheap. I would not want to use a heavy flash on the hotshoe, everything creaks and bends.
This is the critical part. I was worried about unreliable firing, but there have been nothing to report so far. Over the last month I have been using these extensively, and I have had no cases of the trigger not firing when triggered. I have had the flash not fire because the flash batteries were running low, but the wireless is not to blame for that. Only once has the flash fired autonomously, I do not know if it was the trigger or the flash that went weird.
The farthest I've tested is 20 meters outdoors. No problems.
With the Ricoh 500G's leaf shutter I get sync up to the full 1/500 and I don't seem to lose any light even with a full power flash burst. With Canon G2 and Nikon D40 I get sync to 1/1000. At 1/1000 I lose a little light, but not so much that it isn't still extremely awesome to sync that fast esp. in full sunlight. At the next speed (1/1260?) it fails everytime.
I hope this is useful to someone. I you have any questions, just ask!