The reason that there is no easy solution w/regards to RFG and boutique fules is all of the lobbying interests involved. DOE and USDA also have a heavy hand on any EPA policies in this area.
Here is a link to a map of RFG areas.
http://www.epa.gov/otaq/rfgmap.jpg
"I would be more concerned about HOW is gets there and what is can or is using the same path."
That is one of the concerns with replacing MTBE with ethanol. When there is an underground storage tank leak (even with new tougher rules it was found (GAO?)that only 30% of tanks comply); ethanol would be preferentially degraded by bacteria over the toxic aromatics-benzene, toluene, xylene, etc. This preferential degradation would allow the toxics to be transported farther and possibly impact more wells. There are also other air quality issues with ethanol due to its hi vapor pressure and combustion emissions of acetaldehyde which is a carcinogen recently upgraded by EPA
The issue with MTBE has been its high water solubility/low sorption coefficient so it is transported at the outer edges of a plume and thus may impact more wells than the 'toxic' fraction.
The problem is we don't know the ratio of wells that would be impacted by toxics under ethanol blended RFG to that with MTBE blended RFG.
MTBE is a problem because at relatively low levels , the smell/taste deems some water supplies useless without remediation. However,as outlined above the use of ethanol (under an MTBE ban) might not be the savior either.