I've used SugarCRM in the past, it's good software albeit a bitch to get everything setup and working exactly how you want it. So far as if you customer really needs it or not, that's really up to them.
How do they currently manage their customer relations? If they have some other sort of system in place, and its working, then I'd say leave it be. If their current system is either ineffective or non-existant, then maybe SugarCRM is the way to go.