CA Prop 37 -- More complicated than you think

Boy was I thrown through a loop today when two out of three professors on a panel at school advised voting NO on CA Proposition 37!  This information came just a week or so after visiting farmer and local hero Steve Sprinkel who advocated so heavily for it.  Must investigate further...

There are other lists of the pros and cons of this issue but I wanted to focus on the grey areas raised by this initiative in the panel today:
-Labeling a GMO isn't a yes or no question.  Prop 37 would instate a zero tolerance policy about GMOs, however in Europe their GMO labeling has some leeway which makes it loads easier on the farmers.  The range of appropriate and inevitable GMO cross over and influence should be accounted for in this bill.
-Biologically, eating GMOs have not been shown to cause use harm, but also doesn't come highly recommended.  In other words there are no clear risks, it just seems like not a wise thing to do. Other things have shown higher risk: mercury and arsenic.
-Labeling GMOs would probably decrease the number of GMOs sold which would in turn reduce the amount of pesticides used in production which does have clear health benefits for those living near the farms.
-The bill doesn't enforce labeling of meats that were fed with GMOs (what 90% of GMO products are used for)
-The bill is not clear on who the enforcement of this regulation would be set on.  Some think it is set on the manufactures, which would be relatively easy for them to do, but others think that the regulation would be forced on the individual grocery stores, which seems impractical and unnecessary. 
-On the Farmer side those who stand to be hurt the most from this legislation are the small scale conventional farmers while the small organic farmers will benefit the most.  This is why you see advertisements from "small farmers" both in favor and against the bill.
-Ultimately I think that most other voters and I will think about how this bill will affect ourselves.  Personally, I want to be able to walk thought my grocery store and know what food is genetically modified or not, so I will vote yes on Prop 37.