we use PAYE because our nanny earns too much to use the simplified system (the limit is less than £160 a week so you are under it).
If we could've I would've used simplified like a shot as it looked like the tax tables are easier, you dont have to do a P11 (long complicated form that has to be updated every month about pay, NI and tax) and generally you are treated more like an individual who happens to have childcare and less like a small business who has a payroll dept and should know what they're doing.
you get a cdrom either way