IRPilot2006
I think you are getting yourself confused... in earlier posts you extolled the virutes of the french system whereby you get radar derived traffic info and even avoiding vectors when receiving a FIS (paraphrasing your words from 4 posts ago)
In the UK you can receive a RIS or a RAS regardless of whether your are VMC or IMC... yo ucan have a RAS on a gin clear blue day if you so please, ... if you are a civvy, you need to be IFR to receive a RAS (I believe that's still the case..... I work in class A only now). These rules do not change what the service provides, nor the obligations of either the controller or the pilot.
Regarding terrain separation, we will not provide a RAS (i.e. a service under which we can issue vectors) to A/C flying below specified levels (used to be called radar vectoring charts, might still be), so yes you the pilot are ultimately responsible for terrain separation in class G, but we will not put ourselves in a position in the first place whereby we will vector you into Cumulus Granite-is.
None of what you have said makes any difference - if you want traffic called out to you, you ask for a RIS... if you want advisory headings to provide radar separation, you ask for a RAS. The receipt of either of those services does not negate the pilots responsibility to use the mark one eyeball to look outside as part of his overall scan (unless you are in really thick IMC, when it's a bit disorientating to do so!).
If you are happy looking out the window, and only want updated on major aerial activities, or strange weather phenomena or airfield unserviceabilities etc etc or want to participate in an alerting service - you ask for a FIS.
You can ask for a RIS or a RAS for any reason, a good one may be the fact that due to tasking, you are busy heads-down in the cockpit for longer than usual and are therefore not able to maintain the full lookout that you normally would.
FIS, RIS and RAS are laid down in black and white, they are very simple to follow, I for one do not understand why anyone should get confused.