Stephen, I am not 'telling the industry' that they need to install IP68 rated fixtures in trees. What you choose to install is your business. My point is that these fixtures are built to the highest specification of water proofing, perhaps over-specified, but the point is that they are not going to leak or allow moisture ingress. That is a big plus when you are installing fixtures in all sorts of applications, in all sorts of environments and using LED lamps. As for the other manufacturers, I would like to see these IP66 ratings you speak of. Most manufacturers don't bother with the trouble or expense of IP testing their fixtures. I am not the only person who has had moisture ingress issues with all sorts of fixtures from all sorts of manufacturers, just ask around, it is one of the most common complaints out there.
As for your experience with the 203 (50 to 80 down lights is an avg. job here, not a year) Do as I suggested. Cut open a stem and take a look at what comprises their "anti-siphon system", perhaps when you see both lead wires stripped of insulation inside the stem you will realize how easy it is for those conductors to come into contact with each other and cause a short, right out of the box. (not caused by incorrect handling or installing either). In one season I had a 3% failure rate with this issue, once I discovered why I contacted Lumiere and was never provided the courtesy of a follow up. A really poorly conceived 'feature' in my opinion and one that resulted in my taking my business elsewhere.
The way I see it, there should never be an issue with pursuing the best possible products for any given application and I won't settle (on behalf of my client's) for anything less. Far be it for me to tell you what to use, but don't criticize those who strive to bring new, improved and innovative products to market for the benefit of those who are looking for them.