Just gave Deric a thumbs up as his answer really addresses the core question regarding rates and comparison of loan products. A mortgage professional can quite easily produce you a very detailed report analysis of your specific situaion so you can weigh out your options and compare products, interest rates and costs side by side.
I concur that FHA rates are CURRENTLY lower (in most cases) than conventional; however a few years ago FHA was typically .50 more than conventional. The message is that rates/market and investor appetitie (desire to buy) one product versus another can fluctuate at any time. Knowing which is a better solution for your financing needs is best addressed directly with a mortgage professional who will provide the information with no expectation/obligation or pressure.
Best to you,