More than 4 classes
I work for an organisation that manages multi-millions in the public sector, and everyone in the team wants to move to Xero; unfortunately, with the nature of our finances, we need many cost-centres to sort the finances relating to each program. If Xero had the option of more than 4 cost-centres, say up to 50, then we would move to Xero in a heartbeat.
At present we use Reckon as it allows for unlimited cost-centres, as this is the main feature we absolutely need for running our finances. We also use Xero for payroll but then do a manual journal to move this to Reckon and apportion across the many cost-centres, which, as you can imagine, is quite time-consuming.

Hi Sydnee, when you say cost centres would you be referring to the Tracking feature in Xero?
Might be worth having a play in the demo company, but it sounds like you could possibly use one Tracking Category for Cost Centres, and list each of your cost centres as a separate Tracking option. You can have up to 100 options within a single Tracking category. See more on the set up in Xero central.