I have been keeping veileds for quite a bit over 10 years...and other chameleons for quite a few years before that....and I have seen and heard what happens to veileds when they are kept together as a pair...and even when two females are kept together. One almost always dies. It may take some time...but it happens. There are some people who (with very large cages) have been able to keep a pair together...but that's the exception to the rule....and do you want to risk yours being the exception??
Here are some other opinions for you...
Cohabitation (the first one is about two different species, its the following ones that I'm referring you to)...
http://www.chameleonnews.com/index.html
http://www.chameleonnews.com/year2003/july2003/cohabitation/cohabitation.html
"There will always be a low grade stress level for the loser who is being dominated. The winner, though, is not free from this stress as the winner must constantly maintain his dominance."
"health issues related to co-habitation usually manifest themselves over time and indirectly. This makes the official cause of death something other than co-habitation. And the problems become noticeable to the keeper long after the chameleons have been together thus, in the keepers mind, ruling out co-habitation as a source of trouble."
http://www.chameleonnews.com/index.html
"Myth #3: Chameleons can be kept in small groups rather than individual cages.
Fact: Very few chameleons will tolerate the presence of conspecifics. A few of the tiny members of the genera Rhampholeon and Brookesia are notable exceptions but even then, two adult males should not be housed together. Virtually of the commonly kept species such as the jacksonii, pardalis, calyptratus, quadricornis, melleri, deremensis, lateralis, gracilis, dilepis, and even the tiny ellioti, require individual housing and this means visual as well as physical isolation from other chameleons. To the eye of the novice two chameleons might appear to be getting along but the stress is there and the result will be an early death. If you can provide a large, walk-in type cage, you might get away with it for some species but this is rarely an option for novices and should only be attempted by those with extensive experience in chameleon husbandry. Only experience lets you identify the subtle symptoms of chronic stress before it’s too late."
You said..."There are - as im sure you will agree - a great deal of differing opinions on how to look after our beautiful Chameleon friends"...I do agree with that...but look at the success records from these people. How long did their chameleons live? How healthy were they during that time? Did they reproduce? How did the hatchlings do (healthwise, lifespan, etc.)?
You also said..."some actually say that there is, as yet, no real right or wrong answers to keeping captive bred Veils as there really hasnt been enough study carried out"...there has been quite a bit of research lately done on them and although there are some grey areas left to do with veileds...again the proof is in the pudding. (Ask the same questions as above.)
You said..."the female has lived with the male in the pet shop and with the pet shop owners for almost a year before they came to us and the female laid a healthy batch of eggs whilst there. Since being with us she has also laid a healthy batch of 35 eggs! Not bad for a Chameleon that is "stressed - possibly even dying!"...as I said the death is not quick...and many (not all) pet shops have no/little idea of what they are doing.
You said..."This is why I ask these questions - most studies say they shouldnt be kept together - but up until now mine have been fine - and I have read many reports of others being fine too!"...you may be lucky and have two that tolerate each other...but the proof may be in how many years they live and what health problems they go through during those years.
You said..."ooooo .... and i forgot to add ...... in their enclosure (which is pretty large) there are plenty of places they can go to hide from one another if that is there will!"...I'd rather have mine "free" to move around the whole cage rather than to have to spend 70% of their time hiding.
You said..."If I put a partition up so they cant see each other they will surely still know that each other are there - through memory and smell!??!!"....well...I would say they have a memory of kinds...but their sense of smell is supposed to be devolved.
There are other possibilites of each "knowing" the other is there.
http://www.altaranchopet.com/handouts/Reptiles/chameleon_care.htm
"HEARING
Like snakes, chameleons have no external ears. Airborne sound vibrations are absorbed by a membrane of skin on the side of the head, directing them to a bony plate inside the skull. The bone (pterygoid plate) then funnels the vibrations down a tight, convoluted pathway to the inner ear. While the ear can sense sound ranging from 100 to 10,000 cycles, it best "hears" between 200-600 cycles, about what a snake "hears." In other words, they hear sounds more like a tuba makes than a flute, not responding to sound frequencies above middle C on the piano.
SMELL
Chameleons have devolved their sense of smell, relying on vision for locating prey and predators rather than smell or hearing. While other reptiles that rely on smell to help them identify objects in their environment, chameleons have only the vestigial remains of this vomeronasal organ, called the Jacobson's organ, which is inoperative."
If you want more opinions, try posting on this kingsnake forum...it gets more action than this one...
http://forums.kingsnake.com/forum.php?catid=44