Well I finally gave in and installed Chrome to test the site. And it worked Don't know why firefox didn't like it, and now I have completed the sign up, firefox works fine. There must be something odd going on.
Anyhoo, I used the opportunity to invest my GHX earnings into gold. It looks like it takes up to 48 hours to confirm when paying by BTC, and withdrawals to BTC is Coming SoonTM, as are the debit card and invoicing.
But it's a nice idea and less volatile than BTC (I hope).