Seriously, If you look at the history of captive breeding of monitors, you will find, that its not Tree monitor eggs that do not hatch so well, its all monitor eggs.
You will also see, that those who understand the biology of monitors, hatch their eggs no matter what species they are.
If you look at such commonly bred species as Ackies or tristis, you will find the same, not so many hatch. In other words, there is a lot of egg failure in even monitors bred to the upteenth generation. Of course, those with experience have little problem hatching them. Those without, often times fail.
Its fun to watch, but those that have trouble(like Rsg hahahahahaha), seem to have trouble across the board) and those that don't, are very much the opposite, have success, across the board.
Personally, I will take any species of large eggs(that includes your tree monitors) over any species of small monitor eggs. They are soooooooooooo much easier. The reason is, there is lots of room for error.
I think perhaps, you should ring up the fellas in indo and europe(prasinus breeders) and ask what their hatching rate is, and compare that to someone here breeding ackies. I bet, ackies have a higher percentage of loss. but then, they lay so many more eggs.
About indo monitors having eggs that are hard to hatch, again, thats a joke. just look at Goons rudi eggs, she hatches them on a shelf, no incubator, in the sun, or partially in the sun, with no hatching experience, and still manages to hatch a fair percentage. It seems the truth is, you have to have hatchable eggs in order to hatch them. And well, most Indos are leaf nesters compared to dirt nesters. But most keepers of indo monitors, think they too, should be nested in dirt.
You know if I nested my Lacies and Croc monitors in dirt, or even, any store bought junk. I would not have hatched a single one. Thanks for considering this. FR