This is one of the reasons why we rejected the GT program as being sufficient by itself; DD needed a full year acceleration AND the gifted program.
I'd count acceleration as a form of differentiation. And yes, it was utterly essential for us too.
As a matter of options open to serve a gifted kid, differentiation into acceleration should be a continuum. But be aware that in edu-speak, differentiation and acceleration are very different things.
We've seen skillful differentation and successful acceleration within (and in parallel to) gifted services, each leading to positive outcomes. The most skillful differentiation our kids have had have nearly forced subsequent acceleration. We've also used acceleration in places where the differentiation was not implemented, implemented on the curriculum side and NOT on the instruction side, or was otherwise damaging.
