It should be managed to the benefit of ALL parties.
If the controller feels that they have reached a limit then access is denied. I only ever denied access to my CAT D airspace when I was too preoccupied with other tasks.
As far as not separating IFR/VFR. I was ALWAYS of the opinion that regular heads up and a little bit of judicious holding of VFR traffic ( the airmanship of which I had no idea) was preferable to letting it ramble freely in the zone whilst TCAS TA's or worse RA's were reported to me. TCAS doesn't know you DON'T require to separate.
By all means allow access.....but if you can't ...then don't.