From my experience Dick, in similar airspace where IFR are mixed with VFR, they simply advise the IFR aircraft where the VFR are if they are nearby and are perceived to be a threat. The issues with that are that the controller hasn't necessarily spoken at all to the VFR pilot in class E airspace so he doesn't know who they are or where they are going or even verified their altitude, so they will need to report to the IFR guy as such.
You'd have to think the risk was moderately low if you're up high as not many VFR are within the 8,500ft to FL180 but you never know do you, perhaps a VFR L39 from the AOPA L39 owners club could be playing up there! The VFR guy only needs to be capable of comms with ATC and not demonstrate it unless I'm mistaken so who knows if he will respond to requests from ATC...