I prefer to call them Swiss because it's correct and easy. Calling them Swissies sounds stupid, almost as stupid as calling the currency chuffs. In some parts of England, chuff means fart. I don't think Franc is too difficult too say.
Swinglish is already in common usage to describe interesting constructions of the english language.
Dan, chill out, it's not aimed at you. I would have written the same thing regardless of whether you'd already written something in this thread or not. There are many "chuffers" and I've complained about the use of "swissie" since long before I met you.
I was once working for a serious electronics distribution company that provided a advert brief to the advertising guy for an electronics magazine scribbled on a scrap of paper with a sketch and "we will be chuffed to serve you" as an example of the message. We honestly didnt expect him to add a photo of a steam engine and use the slogan verbatim...
don't forget that 'swissie' is the currency markets affectionate name for the Swiss Franc so that rukles out using it to describe people - face it, the way the Swissie is depreciating in value against the £ you would have lost an arm and a leg in the last few months !!