Hi David
A good article as others suggest.
I think your observations regarding using digital as a tool reflect a lot of different aspects of digital and its encroachment on traditional camera image taking.
The argument about the mb size I think is soon to be a non issue, as we are very close to the 20mb 35mm camera. I would use traditional film as you are right it does contain more information. But if the budget is there a medium format camera with a digital back will give you the file size to make the type of prints you are suggesting. No it will not match a 4x5 negative or 8x10 negative quality you were speaking of .but the advantages of looking at the work on site and sending files to counterparts makes a lot of sense to me.
Maybe two cameras , one digital for the grunt work and a good medium to large format camera loaded with film for the quality records.
Regarding storage. Of the 3000 images plus you are storing , how many of them are of real value. I think recording the important images to an image setter may be of value.
If this is too simple of an fix , I do imagine that the storage and filing of digital
images will improve as well as the price of the equipment itself.
Regarding film storage, traditional black and white and colour, if these images are not properly maintained there can be major problems, lets not kid ourselves here.
I think your profession is on the digital wave and much like a lot of our facets of photography , digital is here and is going to stay.
I think if one can mix the best of both, digital/traditional , you are on the right track.
If you are using laptops in the field then I think you will be able to use a digital camera as well.

I think the proper tool for your job would be the one that suits you the best and the people that have to work around you. Whether it be digital or traditional.