Do it yourself. It's NOT HARD at all. I had the fear of god in me that it would be horribly difficult and I would starve if I did it myself. I was wrong and I have a lot more coding than you'll have to do.
I'm not sure how much per year or per month you are spending on your biller but there are easier options.
Use an online program like TotalMD that's only $99/month. Straightforward, easy to use.
The thing you will have to do that is the more time consuming part is chase down denials. Hopefully there won't be many and with 99% of your codes being simple E&M codes, it shouldn't be tough. I rarely, if ever, have a denial for an E&M code. Mine are always big operations where the insurance company is trying to avoid paying me.
Of course, a lot of people have good results with Office Ally as well. I just don't know how that works.
In the end, you can do it. It will save you a ton of money. You KNOW it is being done correctly and every claim is being pursued appropriately.
My wife does it for me and she easily spends less than 10 hours per week doing it.