From what Ive heard; microlights only get in the way most of the time.
As for whether it makes difference? Well, yes! Ok it doesn't keep VFR out unlike LTMA for example; BUT it does keep instrument traffic inside controlled airspace which I believe is the main point behind the change. Yes, VFR will probably be allowed to enter CAS in VMC, subject to instrument traffic as always. There are new VRPs coming in for various points of entry, so there will be new places to orbit at
.
Remember, this airspace change isn't designed necessarily for the current traffic levels, but its there in preparation to handle the inevitable traffic increase over the next 20 years or so.