It will help as a rough guide to exposure. It will not help in fine-tuning the exposure because the shadows and highlights response of film is different from that of digital.
For difficult situations - a high contrast scene where you have to correctly place the highlights or the shadows - a spot light meter, or an incident light meter, correctly used, will give you error-proof results while a DSLR will give you a guidance which will not guarantee the final result or will not optimize the exposure: for instance, you might close exposure until your DSLR tells you that no highlight clip occurs, if you use that exposure, you are going to block some shadows "more" than you would have by following another exposure method. Your film, slide film included, has a wider highlights range before falling into pure white so you can "open" your exposure more than what is suggested by your DSLR.
In general the best way to expose with a digital camera is ETTR ("expose to the right", open as much as you can before highlight clipping) which is the roughly equivalent method to "highlight placing" with a spot meter when using slides, but the two media having different clipping points the exposure between the two is not replicable.
To sum it up: for generic exposure (you let the camera let the averaging) it should work, no more no less than measuring with a film SLR (FSRL). For "fine tuning" I would not use a DSLR as a light meter. I wouldn't use it as a "polaroid" as well because in high-contrast situations I would end up always wasting some useful stretch of the characteristic curve on the highlights.