I don't buy that about differences between digital and film ISO. ISO is a norm and cannot be different from one camera to another.
I tested lots of camera meters against each other and handheld lightmeter, there are differences, but nothing drastic. Some film cameras are calibrated to err towards over-exposing, typically low end cameras because they are supposed to use negatives. Others will under-expose because it works better for slides. Other than this kind of bias, they should all measure identically, digital or film.
I check my cameras from time to time to see if they are aligned. I compensate using exposure compensation on the camera, as I almost never use it in actual action.