Similarly, I have raised this issue to mixed reactions. I have no idea of the physics of it.
But, from my experience in water ranging from the bathwater Delta to icy Tahoe (and sometimes going from back and forth from one to the other), the answer is Yes. At least feel-wise.
My board also seems to ride higher in the colder water and it is harder to initiate and hold an edge without sliding out. So, the wake may be similar or only slightly smaller in size, but it feels smaller because of all the other variables (harder water, cold body, etc.).