Yes, you can use your DSLR as a light meter, transferring settings from one camera to another. I own a Widelux 1500 medium format panoramic camera, and do this all the time with great results. My exposures on Fuji Velvia are dead on are dead on. When i first started i thought there would be some adjustment factor, but I had no issues.
I did this because I did not want to carry a separate meter, or pay for it, and I was going to have a DSLR with me anyway. Now that I think about this, I started with film doing this with a Nikon D90 about 15 years ago. The Widelux does not get much action as of late, but I still like to use it from time to time.
Obviously flash exposures are not gong to work this way.