So my initial thoughts when I started reading the thread, in relation to G were:
1 – Seems like a really nice bloke
2 – Fair play to him to raise some cash (yes despite him being sponsored)
3 – Tax evading scumbag
But, as the principle of taxation is to pay for the services of the country you live in, then if he mainly lives in Monaco then fair enough really. But, keeping your citizenship is another thing – if you want to go live somewhere else, and pay their taxes instead, then I think you should take on their citizenship and give up your old one.