rbridges
En-Route
I've already stated the risk--
What exactly is the benefit of operating on an IFR clearance restricted to VMC, vs being a VFR aircraft practicing instrument procedures? Both are restricted to VMC. All players know the latter is VFR, while the former is IFR only as long as he is in VMC. I would hazard a guess that putting "restricted to vmc" on an IFR flightplan does not get passed to every controller handling the flight.
How about hearing from a controller? They're the ones that have to keep airplanes from trading paint. Is it worth the potential confusion?
I've done many IFR flights and been in VMC the entire way. If I were trying to train, and all I had was a non-IFR plane on a CAVU day, I don't see the harm. I wouldn't recommend filing IFR if it looked like you could be hitting clouds or IMC, but that's just my opinion.