Have you actually been on the Deloitte version? Unfortunately, unlike the other channel partners the Deloitte version is paid only. There's no free trail either, so can't sign up.
Xero does appear in screen shots of other versions too, but it can't be added to the dashboard as it says "coming soon" instead of an add button. Maybe you're right and the Deloitte version is different as it's paid.
Not sure if you have to pay £125 per month to get full access of Accounts or just the £25 per month to get the dashboard? Seems expensive but I guess Deloitte is using it as an up sell for the "Dedicated Financial Expert".
9SP Price at posting:
4.9¢ Sentiment: Sell Disclosure: Not Held