The DDI's are build to solve one problem, and are used only in places where they are needed.
the DDI solve a problem of one HWY traffic flow MUST not be interrupted, while the merging traffic makes a left turn.
the DDI by design will not work if the secondary road traffic is too big.
DDI will not work well on interchanges of 2 large HWY's.
they are better then the regular interchanges that have a 4 way stop light in each side.
are better then the ones that have a control light on the on ramps.
and are worst then a traditional full flow interchanges.
here are some read: Diverging diamond interchange - Wikipedia, the free encyclopedia
No. It would be failure to yield. Local quirks such as this are particularly dangerous, IMHO, because people are so mobile nowadays. You can't count on the guy across the intersection knowing what you're gonna do; he might be an Israeli from Minnesota