Unfortunately the problem with rumours are that they are usually created with a mixture of wishful thinking and clap-trap.
Last year I tried to get some information on the conversion from the CAA, however with the JAR mess they hadn't got round to the helicopter specific issues. I was informed that some of my hours would count but the helicopter instrument hours would not. I was then referred to an FTO who weren't very helpful at all but did seem willing to contradict the CAA and assure me that I would have to do the full course with full payment with no regard to my flight experience.
Hopefully now all parties would be able to give you a definite answer.
As always you need to contact the CAA and get a written assessment of what your conversion requirements would be, and then see if an FTO agrees with the assessment.
One final point, if you were a qualified pilot prior to JARs were introduced I am led to believe that you come under CAA CAP 54 of old, in which case your helicopter hours would count i.e. x-country,total flight time and some instrument time towards the FW requirements.
I hope this is of help...good luck