Been flying for 20 years on my PPL (VFR). Whatever you end up defining as your personal minima, please do the following: Go with an IFR rated instructor on a flight in really marginal (VMC) weather, if not full IMC. Will give you a feel at how things are, a feel you'd never get on your own without panicking, and will also give you some training in staying safe should you get cought in the soup one day.
Done this a couple of time myself, and found to my great amazement that I'm fine maintaining heading and altitude, doing turns, tracking VORs and ILS, all in zero visibility. Last time we broke out of the soup at around 200' AGL being only half a runway breadth off.