It doesn't necessarily help to be legally informed or not unless you change the role of the jury completely. The law is already set and interpreted by other parties, the only question is about if the jury feels an open ended threshold of doubt has been reached. One could argue to have a class of people that try to rigorously decide what is reasonable doubt based on additions to law that try to quantify doubt but one could just as easily argue finding what society finds to be reasonable doubt is something better answered by normal people instead of a special class and trying to codify what doubt is for every situation in every law unreasonable to do accurately and keep up to date.

I don't think one is inherently right or wrong, it's more a match to ideals. The important thing to note with the current jury system in the US is it's actually preferred they aren't specially informed in law (beyond their given role on the jury) as anything related to legal interpretation is supposed to be done by the rest of the court anyways.