I don't think any of the responses advocate not speaking with service providers if operating in IMC. (Although I really do question the value of a true basic service for any credible level of traffic information)
The key point (and directly responding to the OP) is, telling ATC which flight rules you are complying with (when seeking a service in Class G) is not particularly relevant. Ask for the service you want is very relevant. Sometimes, if the service is not forthcoming, mentioning you are in IMC joggs you up the priority list for a higher level of service.
It is also worth remembering that asking for a deconfliction service can wind up with you being vectored all over the place (or in the South East can even be nigh on impossible for a controller to provide - 5 miles/1000 ft and IFR terrain clearance is pretty hard to achieve in the OCK BIG slot)