Thanks HoppyUK, I've looked at the Strato II triggers and think it would be a close call between them and the Cactus v5. Both appear to do the important things well - reliably trigger the flashes and have good range.
However, for me, the fact the Cactus units can act as both a transmitter and receiver, and the simpler 'one pin' triggering system that enables them to work with any brand or old flashguns, swings things slightly in their favour.
On the other hand, I suspect the Strato units might have slightly better build - not that the cactus is bad, but the Strato appears to be smaller and maybe made from a better grade of plastic
I'd put both these brands well ahead of the 602/603 units - the absence of a locking ring to secure them to your camera or light stand is just plain silly cost-cutting that I guess would quickly become very annoying when using them anywhere outside your living room. Other things, such as positioning the on/off switch in a place that can't be reached when a flash in mounted, makes me wonder what the designer was thinking about
I agree that using a cable to connect the cactus units to the camera (when using a flash in ettl mode mounted in the camera hotshoe) is not perfect, but I still prefer it as the on-camera flash feels much more secure when mounted this way (able to withstand a few knocks and bumps). I bought three screwlock cables for £10 in total. They are just the right length to connect the camera's pc port to a cactus velcroed on top of the on-camera flash, and a big improvement on the very short supplied cable.
Even if using the cactus on a light stand with a brolly, I still usually connect up the cable rather than mount the flash on the cactus hotshoe as I feel it directs the flash more into the centre of a brolly.
Anyway, these new canon flashes with built-in radio control might change things in future (if we can afford them, lol)
