I don't know anything about Greece, but speaking of my country of origin (Czech Republic) is quite a big problem to set up credit card payments, not speaking about much bigger administrative burden and costly process of setting up company.
As zerostar07 said, the bureaucracy alone makes it a nonstarter. In the UK I get my personal HMRC contact, whereas in Greece you have to get up at 7 am and only hope you will get whatever you want done that day.
Also, Greece doesn't generally encourage entrepreneurship that much. For example, I can't email an invoice, I have to actually mail the actual physical copy, which I have to write by hand, because I have a book of invoices stamped by the Eforia (the Greek revenue service).
Plus, setting up the UK company took 15 minutes and as many pounds, whereas I have no idea how much it costs in Greece. Friends who've done it told me to stay away.
The bureaucracy and costs make it a bad choice when your clients are not in the country. The tax law changed at least 3 times (I stopped counting) last year.
For now, yes. But if Greece leaves the Euro in order to devalue her debt (considered by many as inevitable), the contracts of Greek companies would likely be forcefully redenominated to "New Drachmars".
Of course, no one knows how this will play out, but I think it would be very hard for anyone to touch a UK limited company's contracts and sterling holdings, regardless of who it's owner is.
