Will you photograph your subjects with the same lightning and background every time? In that case you could use the DLSR to see that it's ok and then continiously use the same ratio during sessions.
I don't think that you are sheating when using a digital camera. But you should probably know that you can not use the old 'What You See Is What You Get' - thing.
Film, as you know have other dynamic data than digital and the display won't be able to show exact how the image looks like. You may use the histogram.
Me, I use a Flash meter and just take a reading on the lit side of the face and increase the exposure with one f-stop (so it becomes lighter).