Yep, I have some friends done the same. I reckon it's a claytons way of giving up......... You don't stop 'smoking' & you don't stop the nicotine intake........ so you don't actually give up.
One friend has convinced himself he's doing good when in reality he still chain-smokes when alone, & only uses the e-fags when around others.
Giving up ain't easy & the only way any method is going to work relies on two things. 1. Making the clear decision that you no longer smoke & 2. No longer smoking. Everything else is just help along the way.
Giving up is only a temporary state of mind at the beginning - you have to move on from being a 'giving up smoker' to being a 'non smoker' or 'ex smoker' and that's state of mind too.
Says Cuppa - Born again Non Smoker. :)