And I mean that in a sincere way.
Data sheets show FP4+ also has a big shoulder, while most other films are straight lined after the toe (according to the sheets).
In 8x10, you're not going to notice it that much anyway. So FP4+, or even Shanghai GP3 is going to be fine.
If cost and grain are both issues, why not go back down to 4x5 T-grain films?
While it is possible to make the generality that faster films have a larger RMS granularity than slower films. One cannot make a similar statement that all films of the same speed have the same granularity. Older style films from second tier manufacturers are granier than the same speed films from Kodak, Ilford, and Fuji.
I asked the same thing this morning...
I have used both in MF. I like both and they both seem to expand a contract well.
It may simply be luck or the stars aligning or how I hold my mouth, but FP4 just seems to work easier/more reliably for me.
Heck for all I know though the next time I try Delta 100 it may finally click.
In terms of tonality and flexibility, they are very similar - unless OP is using a Pyro developer such as WD2D or PMK, in which case Delta 100 will lose a lot of speed compared with FP4+. While Delta is finer grained than FP4+, since OP is talking about contact prints from 8x10 negatives, grain, resolution and sharpness are non-issues. Delta has better reciprocity characteristics than FP4+ which may be of some value to OP in 8x10 if long exposures are anticipated.
As an aside to OP (Mark), if you use small or medium formats and you hate grain, do not rule Kodak out since TMX is the finest grained general purpose film around. It is noticeably finer grained than Delta 100 (Fuji's Acros falls in between), finer grained than Pan F+ etc.
As for the purist vs tabular issue, it will probably disappoint some people to learn that the films they consider "traditional grained" such as FP4+, Plus-X, HP5+ and Tri-X are not as traditional as they once were. The current versions of these films are more like hybrids of traditional and tabular technology. Perhaps "semi-tabular" would be a more accurate description.
Back in the day when the tabular films first came out, I was told that you only really benefit from them when they are matched with a developer designed for them, otherwise they behave like the more traditional films. Given the response in this thread has been quite, ahem, diverse, I might get a bit of a wide ranging response :) but I would b most interested in hearing from the tab-fans.
...it will also depend on which developer you use. Since every person who has replied likely uses different agitation methods, developer type, concentration, temperature and container types, the results will vary. My experience with Delta 100 has been favorable for fine-art prints and portraiture, but I don't like it for general use or street photography because with my methods, way of shooting, developing techniques, etc. shadow detail has fallen off the map and the highlights hit too vibrantly and my mid-tones get lost in shadows.
But since we're talking about 8x10 contact prints...you'll notice nothing in difference in terms of grain -believe me. I can't see grain in fp4 or delta with a 35mm neg blown up to 8x10 to the point where I have to try to focus with a grain focuser until my back hurts trying to find any of the stuff. I'll give you one of my kidneys if you can prove otherwise.
...really what it should boil down to is characteristics, not grain, which is what you were kind of originally asking. And I would say that FP4 has a more classic look with a longer range of midtones and better controlled highlights, where Delta 100 has a more "digital" feel to it, where it's seemingly more crisp and sharp. I prefer FP4 for this reason, but that's just my opinion. Unfortunately, you'll likely have to buy a box of each and check it out for yourself.
Are you shooting medium/large format or 35mm? If 35mm and you "hate grain" then I would most definitely go with Delta 100. As many have said, they are more similar than different. I shoot MF and much prefer FP4 which I still find extremely fine grain. I develop in FP4 in rodinal frequently to bring out its grain and amazing sharpness. But if I were shooting 35mm I may not do so.