I have flown both on and off over the years, but fixed wing was mainly agricultural. That puts the FW into a similar environment as the utility helicopter, and the same skills are required.
I value the experience from both. In my opinion FW will teach you to think much further ahead of the machine. It may take longer for things to go wrong, but you're deep in when it does. RW will teach you that things can go from just fine, to dire straits instantly - and hopefully back again.
I know some say that there's no useful cross credit of experience between the two but for me that's not true. However, watching an IFR airliner fly itself won't be much use as experience if you're moving a drill rig in a helicopter. Being able to move a drill rig may not help you fly to one in cloud either!
I think that any flying time is good experience, and the wider that experience, the better.
Remote Hook, Shy Torque - very profound comments IMHO.