Using a DSLR for metering, especially considering the ability to chimp images in the field, is fine. You will need to calibrate your system so you know what to expect from the film. Do a few calibration test shots under controlled conditions to learn what ISO offset to apply to the DSLR.
I have found that most DSLRs are slightly off when comparing midtones (the 18% gray). One of my cameras is off by 2/3. Now the ratings by DXO aren't even based on midtone, but on threshold. HUH?
In the old Kodak Professional Photoguide, it illustrates how you use various handheld meters and the offset you need to apply to the exposure when you hold it different ways.