I head a small team of web developers and we spend day and nights on Magento however, one thing, which I feel strongly about, is that there should be a full stack developer in house to address the Magento core issues as well as frontend performance issue. As a team leader, I sometimes feel that some of the developers don't think about the other tier whilst working on their tasks and they totally ignore the implications of their work on someone else's work.
Having a full stack developer along with other developers can reduce the project cost and ensure an on-time delivery of the project.
I hope this makes sense. I am open for your thoughts here.