While I agree with EGOL, that no one will be able to do it as well as you given your depth of knowledge on your business and audience, I still think it makes sense to hire an expert.
(I'm over generalizing in a preachy dramatic way to make a point, so take it for what it is.) Smart capable people; we all have the same problem. We think: "Well, no one else can do it better than I can, so I'll just do it myself." But if we don't learn to accept support, and play to our strengths, we can only go so far in our ambitions to build something big.
One of the best decisions I made at 26, was to outsource my house cleaning. Seriously. It's a blessing. And now I just embrace it in every aspect of life, and business. Hiring others to do services, has given me space and capacity to build a better, and bigger business. I can build my own website, do my own taxes, and etc. I can probably build a really good website. But I don't want to be a good web designer. I want to be a PPC expert, and continue to develop that strength more deeply. So I outsource my website and taxes to a professional.
In that same vein, you need a professional PPC manager. Let it be their focus to maximize your campaign's effectiveness, and stay on top of the ever-changing PPC landscape. And you focus on being more you. I bet if we look at the numbers, then just one more extra conversion/sale/client per month would more than pay for the expertise, (not to mention the time you would save).