I agree that the recommended minimum is 600ft for single engine, and many Ops manuals for twin engined operations will specify a ceiling for departure. The ones I have flown with have been 100ft ceiling and the relevant airport RVR departure minimum.
With ref to the quick blast through a thin low layer of cloud to VMC on top, you need to consider your options if your only donk quits. With a 600ft cloudbase you have a chance of pulling off some sort of survivable forced landing (terrain permitting), lower than that and I suggest you would have to be very lucky.
But all this is common sense and not LAW!