Hi Kimo,
I have been keeping and breeding cresteds for a while-well,certainly not as many as some members of this forum.
I have never used any CGD or similar diet and I never had any trouble feeding my cresteds with insects and fruit.
The first important thing is to correctly gut-load your insects prior to feeding.I generally use crickets as a diet but i also give mealworms ,silkworms and waxmoths larvae from time to time to vary this diet.
I also use different fruits in baby food-peach ,banana ,apricot ,pear ,apple...
To give this food to the rhacs,I use bamboo tubes in which i fit a metal lid from the baby food pots and fill it with this very food By doing so ,cresteds don't have to go down at ground level in their viv to find the food .So to me offering a varied food is the second key to success.
The third very important point is to choose a good supplement,which can turn out to be quite difficult.
Insects are already very unbalanced with the Ca/P ratio and you must not use a powdered supplement with extra phosphore ,it does not make any sense. The supplements are also very often either too poor in variety of vitamins or minerals or overdosed with some vitamins,especially D3.
Too much calcium can lead to stones in kidneys in every vertebrate ,and too much vitamins can be more harmful on the long term that not enough.
That is why I use only Miner-All I,T-Rex 2:0 or a new product I found in Hamm ,made in Germany ,CALCAmineral. Other supplements are not fit for geckoes ,to my mind.
I think this is by far the more natural method ,although it demands a little more money and efforts for the keeper than using CGD as the basic food item .Snakes can be fed the same type of prey all their life long ,geckos don't .One day or another ,the lack of variety in their diet could make them fed up and refuse to eat any more.
More,the variety in fruit and properly gut-loaded insects is to me enough to avoid deficiencies .
On top of that,babies fed too early with vitamins will generally die or have serious health issues .I never give any extra vitamins before 3 months old.
CGD has been existing only for a few years .Scientifically speaking ,it is too short a time to evaluate the long-term consequences of an all-CGD diet .While insects and fruit do exist for million years :lol: .We ignore the influence on the lifespan and lineages of the geckos ,we don't know if after 8 years of CGD they still want it so eagerly in a significant number of cases.
It is certainly more handy and has less drawbacks for the keepers than always having tons of crickets at home but I would only use such ready-made food as an occasional treat ,when crickets are not available ,for example.
This is just my opinion and own experience ,I think we the Europeans may have a different approach than the US keepers .Hope that helps a little.