Outsourcing all benefits except 401k

Our company recently decided to outsource all benefits (except 401k) to a 3rd party vendor mid-year.  I'm asking if anyone has encountered this and can discuss items/issues/concerns that I should be aware of.  We are currently on PS9.1 and process pay with payroll for North America module.  The thought is to load all the deductions as general deductions.  That said, what impacts will that have and on what?