Your E111 isn't worth the paper its written on!
It'll provide you with seriously basic medical cover, but it won't cover you for the following-
being delayed,
loosing luggage,
if you need flying home in an emergency, (i.e if someone dies)
legal expences,
cancellation (if you cancel your holiday if you are ill)
if you lose your passport
if any money is stolen
if you are hijacked (extreme - but possible)
hospital benifit (being paid if you spend a long duration ill)
if you die (covers the cost of your body being flown home to a weeping mum and dad)
any questions....
Caroline