Hmm, I haven't touched my LF gear in literally years and it wouldn't surprise me if my lenses are now fungus ridden... I would go look but it's buried in the back of my store room!
I miss those days, I miss 5x4 trannies, I don't miss lugging the thing around!
I did in the early days briefly use a DSLR to preview the scene exposure wise, but I never found it particularly good because I always used the screen on the back of the camera and that isn't calibrated even to the camera's own images. Between competent use of an accurate light meter and a DSLR I would use the light meter anytime, if for nothing else because the screen on a DSLR is horrible
I usually can't recognise the images on my screen later either!
The other problem of course is different cameras are calibrated differently in terms of exposure and exposure response, and then have the aforementioned different tone curves. So for example my D300 has a tendency to overexpose that my D3 doesn't have, while overall the D300 has brighter shadows - and tbh I've been meaning to tweak the curve for ages now.
So it's going to be a little bit difficult to compare a random DSLR with film (and what film?
) And also, digital has more DR particularly in the shadow areas, so I always find film blocks up in the shadows far more quickly, but I'm not sure if that's down to differences in tone curves or just poorer DR (my inclination being the latter).
Remember also if you've used any lens movements on the LF, you'll be needing to compensate for that.
I wasn't aware that some manufacturers calibrate to 12% grey... do you know which ones?
Can't answer your light meter question I'm afraid, the incident ones I've used are all pretty accurate and if they're accurate to even 1/3 of a stop then their performance is linear enough for me