Every teacher in every class should practice differentiation. It's simply catering to varying abilities and developing lessons where there are slightly different tasks for the students to hone in on their strengths and areas of need.
Yes it can be tough to do, but every good teacher does it and unis now are really pushing students to do it well.
I personally like composites. It can be a chance for higher functioning kids to be exposed to extension work and leadership tasks, for kids with various maturity to be with kids at their own stage.