RE: "Testing the effects of such diet for over multiple years isn't something anyone has the funding to do"
These people do: http://sugarscience.ucsf.edu/ [ucsf.edu]
-Artificial sweeteners tell your body "Sugar is coming".
-Your body spikes your insulin but no sugars show up so your body says WTF.
-Your body then has to deal with this excess insulin which makes you hungrier.
-At some point your body gets fed up with all this and starts to ignore insulin (aka insulin resistance)
TL;DR; avoid ALL artificial sweeteners. Glucose is the safest because your body makes itself by converting starch into glucose which get converted to ATP for energy.
After that, Sugar, honey, and maple syrup are the safest.
If you want sweets, that's fine but do in in moderation and stay TF away from artificial sweeteners.