I work on boats in Maryland and we have E10 here as well.
The problems with ethanol are:
It is a solvent so it cleans up everything in your tank. That is fine if your tank is clean, but guess where any trash is going?
It absorbs water. Not a problem with newer cars as their tank is not vented to atmosphere while sitting. Most motorcycles are and this allows water to be absorbed into the fuel.
It can be corrosive. You may have to upgrade to an alcohol safe fuel line. Some fuel hose has a plastic type liner that melts when ethanol is used in it.
It actually is a pretty good fuel, but you will burn more to make the same power as gasoline. So the higher the ethanol content, the worse the gas mileage. If they are really running 50% ethanol, you may find your bike running lean.
As long as you ride your bike a lot, the E10 should not be a problem. I have talked with fuel guys and they say it, E10, starts coming out of phase in as little as two weeks. Yamaha outboards recommends running fuel stabilizer year round. The water it absorbs can damage fuel injectors and high pressure fuel pumps. I have pulled pumps out of boats that are actually rusted because of the water in the fuel.
Just gives you a reason to ride more.
Ride Safe!
FWIW, I have been running the E10 in my bike for over a year and no problems. No fuel stabilizer either, I ride as much as I can.
Watch out if it is really 50% ethanol. I am almost positive you will be running lean. That could definately NOT be cool.