I believe that "Lemon Eucalyptus oil" has shown some definite efficacy, though it's not as long lasting as DEET.
Unfortunately, the natural stuff tends to get less funding and testing overall than the synthesized or the occasional stuff which is concentrated, processed, and distilled from natural. Ok, maybe the exception is exotic Amazon type plants which some drug companies do sometimes spend lots of money and research on.
Large corporations are less interested in things which people can obtain more easily, cheaply, make themselves, etc. They like specialized or patented stuff--easier to make money off of, and at the end of the day, to many larger corporations, banks, and governments you are less an individual person and more a walking $ sign and/or number.
There are things out there which can and should be tested more like Karanja oil.
Re: DEET, Permethrin, etc. lately i lean towards James Marco's stance when it comes to others--people should decide for themselves with all available information. However, it's important to point out that humanity currently lives in an unprecedented age as far as various toxins go. Our food, our air, our water, our oceans, our soils, our living spaces, etc. all contain various toxins, and in many cases or areas--increasing levels of same.
It's also important to point out that modern medicine is still an evolving science with A LOT of room for growth and evolution. Toxicological studies and research generally are kind of "blunt" in the sense that they look for obvious damage and to important, critical organs and bodily systems. Once you get to the levels to do that much damage, it's usually means you're screwed more long term and there may be lasting damage. There are far less studies and research as a whole which research, long term but much smaller amounts, which can over time cause more chronic and SUBTLE issues which can then cause body imbalances hard to pinpoint.
Having spent many years trying to balance an imbalanced body (which happened through a combo of crappy diet, stress, so called (pharma) "medicine", our increasingly toxic environment, etc), personally i try to avoid anything which may add to the toxic load and that includes a very wide range of stuff. It's not fun having chronic and uncomfortable body imbalances...
I would be open to possibly using clothes with just the outside sprayed with permethrin, as it seems less likely to cause issues, however with netting etc i've been pretty fine so far.
Also, the more and more people use permethrin, the more and more likely it is that different bugs will eventually start to adapt to it. This HAS started to happen with DEET and mosquitoes in some places.