There was some story about it not supporting their security mechanism. I think it would be easier to use another browser for trading, to be honest. Pity, because no iPhone users will be able to login either.
Just try using IE, OST techies think that the Safari people are not that important. Simon even defended why they not supporting Safari, no wonder these forums have become boring people are moving with the times i.e. other websites that support all web browsers
It'll depend on the user. I've used most (including Opera), have IE, FF and Chrome installed on my machine, and Firefox is the one I use the most with Chrome second. Tried Safari but didn't like it. So: up to personal tastes.
It's all about preference. I find Safari to be more stable and display websites better (it just feels slicker to me). The time it takes to load websites also differs from browser to browser, not to mention security. Do yourself a favour and try Mozilla, Chrome and Safari. You might like one of them more than IE.
Firefox lets you add plugins, so e.g. I have an ad-blocker and don't see most adverts on the internet - they're just not there. I can structure shortcuts in a way that I like, which IE doesn't do as nicely for my purpose.
Chrome is nice. I use it for some overlapping accounts, e.g. Google manages my company mail but I also have a normal Gmail account, so using two browsers keeps them separate. But Chrome doesn't do adblocking, so it drives me nuts to have a flickering disco when I'm online. IE takes too long to start up and the latest IE menu etc layouts irritate me. Also, adblocking isn't as easy (could be a way, but FF was easier to set up).