[Dave Flowerday]

We've been doing this for a couple of years with good results. As others have said already, all you really need to do is for each loop, read your delta from the encoder wheel and read the most recent angle measured from your gyro and just pretend that you travelled in a straight line since the last time you did the calculation. This happens so fast that you end up approximating the arc with a series of very small straight lines which works well enough for what you're trying to do.

How many encoders are you using? You only need 1 when you use the gyro with it. If you're using more than one you might just be doing unnecessary calculations.