Question

If the universe became transparent at a much earlier time, what would the CMB look like today?

Answer 1

Cooler, of course. Whether less clumpy or not is harder to say. I guess if you believe in dark matter, you believe that inhomgeneities were growing during recombination, so that if the process completes sooner the universe would be less clumpy (more homogeneous) when the photons got loose, and the CMB should be smoother. That's my guess.