Tell me how "weather and speed restrictions" ensure that IFR traffic can see the VFR traffic in front and a little below, when the IFR traffic is IMC, which also makes it hard for the VFR Traffic to see and avoid it.
If the IFR traffic is in IMC and the VFR traffic is also following the rules for class E, both are already separated by definition. Either 1000ft vertically or 1,5 km horizontally (VFR traffic has to stay clear of clouds 1000ft vertically and 1,5 km horizontally). And of course the VFR traffic needs a visibility of 5 km as well. Below FL100 values in this case as VFR in airspace C is extremely rare here and subject to ATC anyway.