“State Legislatures” magazine for October-November 2014 magazine has this article by Louis Jacobson, on whether there is any correlation between type of primary, and type of politician elected to state legislatures or Congress.
The article is very comprehensive, but it doesn’t mention Professor Todd Donovan’s 2012 article, “The Top Two Primary: What Can California Learn from Washington?” published in the California Journal of Politics & Policy, vol. 4, issue 1. That article concluded “The partisan structure of Washington’s legislature appears unaltered by the new primary system.” It also concludes, “The aggregate of all of this did not add up to a legislature that looked different or functioned differently from the legislature elected under a partisan primary.” Donovan’s article is important, not only because it is based on empirical research, but because Donovan was Washington state’s expert witness in favor of the top-two primary, so clearly he is not biased against the top-two system.