Grain is not a factor with a film like Provia, I can print at any size you like and grain is just not any kind of problem at any distance, grain is not a basis for saying digital is better. As for adding digital grain to disguise digital artifacts, with a decent scan you don't have to add or subtract anything. There is nothing to stop you running a noise reduction program on film or any of the other digital techniques, the fact is, done well you don't need to.
You can get superb largeish prints from DSLR's often though with much more effort you can get better on film.
I did a job yesterday in poor light I shot it on digital at 800iso wide open the results are much better than if I'd been using film on any format, so it's not a set in stone observation on my part.
If the conditions had been right MF film would of won.
All these magic tweaks, it reminds me of the skippers of a local craft in my part of the world from the 1800's. They believed brown sails were quicker than white sails, they had their own recipes for dying the new white sails brown, each believing they had a special something to get a bit extra out of the wind. Nonsense of course but they believed in the magic. Software is only juggling the information recorded, a 4000 dpi scan at 14 or more bits has much more in it in the first place. Upsizing with a step here and tweak there is dying the sail brown to me, if you need faster stick an engine on it, use a large lump of film.
From personal experience, the grain of film helps to create a texture to the image especially when printed large.
When printed small I prefer a digital image but when interpolation comes into the picture, the resulting colour information that is added to a digital image tends to come across as flat and graphic.
Film grain seems to fool the eye with its inconsistency, even with its presence the result seems more photographic to the eye.
When it comes to skin tones with an uprezzed image, the film grain actually adds a sense of roughness to the skin which comes across as realistic, whereas with digital what I get is a patch of ...beige. Very flat looking.
I don't know how other people's experience with shooting closeups is, but with digital cameras I still get the sense that the minute tonalities present on skin don't seem to register well. I switched to shooting with a 35mm film camera with Portra specially for faceshots because of this. Maybe I'm hallucinating but I see more subtle detail with film shots for skin
Take a look at the two images below and tell me which one you think is digital and which one is film.http://superhyperreal.com/MerA640.jpghttp://superhyperreal.com/MerB640.jpg
noise/grain and sharpness are not the only factors that contribute to an image looking photographic versus an image that looks more like an illustration or a graphic design image.
All this is from personal experience printing exhibition prints about 4ft by 5 ft using anything from a 1dsMkII, a Nikon D70, 4x5 slide film,6x7 slide film to 35mm neg film.
The problem I have with film (slide film at least) is that shadow detail is absolutely nowhere near digital, and a less than optimal exposure will ensure that your dark areas will register as dense blacks when scanned and printed.
Just a note, I do most of my work with digital though. and I hate dealing with film. But there are certain points where film does have its advantages in terms of image quality.