Titanium cards are smoke and mirrors for the moment. They're out there but if you weren't offered one you aren't "special" to AMEX and won't get 'em until they're released to the "general cardholder population". Supposedly the folks who have 'em are stars, billionaires, etc.
As for the bennies, the Business Centurion doesn't offer US AIR gold status whereas the personal does. I think that's the only major difference. I do find that the biz centurion has better customer service than the personal but then again I find that of ALL the business products vs. the personal cards.
The two card thing is only for the UK. Here in the US you get one card, and that's it. Extra cards cost $$$.