I suggest that you use digital to find your exposures for films only if you find less-than-ideal exposures acceptable.
Now, if there was a digital "exposure preview unit" that you could manually program in a detailed manner to match the technical characteristics of a number of different films, and program different developments as well (preferably by scanning test filmstrips with the unit itself), it would be a lovely device to use for this...but this is not what a digital camera does. A digital camera takes a picture in one way, and that one way is different than the one way any one film would take the same picture. What you see on your camera's screen is a jpeg, and you can set your camera to make the jpeg different than the original capture, just like you can change films or exposure and development to do the same...however, the controls are too rough to be precise. There is no good way to match any in-camera preview exactly to the known characteristics of the film you are using. Therefore, digital cameras are not only less than ideal for use as light meters when using film, but are actually harmful to your exposures. More harmful than an educated/practiced guess? Depends on how educated/practiced you are!

However, never more harmful than a properly-used light meter.