Barry,
Delta 100 is more forgiving then FP4 in terms of exposure; you can overexpose quite a bit and still have all of the tones recorded normally on a straight line.
And just like TMax films it responds more to development changes, making you pay more attention to what you do when you process the film.
As always, do some testing; you need to know what to do in changing lighting conditions. Pick some subject matter in normal contrast, bracket the film at 50, 100, and 200. Process according to the developer (or film) manufacturer's recommendations for normal time.
Judge shadow detail by printing the negatives. The ones that have 'enough' represents the speed you shoot at.
Now it's time to work on the mid-tones and highlights. You know your film speed, so you shoot an entire roll in normal contrast lighting, and when you process, you process one third of the film at a time by cutting it in three pieces. Store the unprocessed pieces in appropriate darkness, perhaps an empty film dev tank, or something.
When you got results about shadow detail that was acceptable above, looking at those negatives - if you had too much highlight density (blocked up highlights) you reduce development, say 10-20%. If the highlights and mid-tones seemed dull you must increase development.
Do this, one third at a time until you reach densities across the board that you are happy with in a print.
Now you know, by spending some time and two rolls of film, how to use Delta 100.
Now you can start experimenting with different lighting scenarios. How does it need to be exposed and processed in harsh lighting of high contrast? Low contrast? There's a lot to learn to get the most out of your film.
What it boils down to is to match it to your paper and paper developer. You can compensate with filtration at the printing stage, but it is always best to start there. The better your negatives are for your paper and paper developer combination, the easier it will be to obtain great prints. Only testing can tell what you need.
Delta 100 can probably be used to look almost identical to FP4 with some tweaking in exposure and development.
Good luck,
- Thomas