By non-technical do you mean someone who has neither previously been a developer nor have a CS/Eng degree? I've worked with both and have found the lack of an engineering background is not determinant in my opinion of the PM. For the non-technical PMs with whom I've worked, the more important factors are willingness to listen when I explain the impracticality of a proposed change/feature and their own willingness to dive deep into understanding the problem domain and customer pain points.