Speech Delay Toddler and Sign Language

Anyone with a toddler diagnosed with expressive speech delay have success with sign language? We have had an early intervention person coming out for almost a year now and we have seen very little progress in his speech. He is just now 2 and she wants us to start using PECS. He picked it up so quick because he is pretty dang smart, but I'm thinking it's not the right intervention for him. I think he would thrive better with sign, but I'd like to hear from some moms who maybe have tried this and how it turned out.