In theory, you should be able to take a D-76 formula, substitute 1/10 the phenidone for the metol, and get pretty similar results. I've not tried that myself, though. To go a bit further, you can substitute ascorbic acid for the hydroquinone (with some extra borax content to get the right pH) for further safety/environmental benefits. The result is
Chris Patton's E-76. I've never used E-76, but I've seen claims that it's more active than D-76, so you might need to adjust your development times.
As to the specific benefits you ask about:
- Homemade D-76 costs $0.10/roll, according to my cost spreadsheet and assuming a 250ml tank, 1:1 dilution, and one-shot use. Substituting an appropriate amount of phenidone for the metol lowers the cost to $0.09/roll. You can judge for yourself how important that $0.01/roll is.
- I don't know about exhaustibility of metol vs. phenidone. Personally, I use all my film developers one-shot and at fairly common dilutions, so I'm not concerned about capacity. If you want long storage life, though, you might want to look into Dimezone S rather than phenidone.
- I also don't know about the practical effects of phenidone vs. metol on latitude.
- AFAIK, grain is the same with the two developing agents, but this certainly isn't a reason to change.
- IMHO, this is the biggest benefit, especially if you're starting to suffer from contact dermatitis. Another option would be to wear gloves when doing your processing.
As Keith says, there are other commercial metol-free developers. In addition to the ones he's mentioned, Paterson FX-50 springs to mind. Rodinal is also metol-free, but it uses a metol precurser, p-aminophenol. I'm not sure if this would be an improvement in terms of contact dermatitis, though. There are lots more mix-it-yourself formulas for metol-free developers, too.
Suzuki's DS-10 and Gainer's PC-TEA both seem popular.
Of course, if you're concerned about contact dermatitis, you might want to look into phenidone-free
paper developers, too.
Chris Patton's E-72 is a modified D-72 (Dektol) similar to his E-76 modification of D-76. I've not used it, though. Personally, I've begun using
Suzuki's DS-14, which works pretty well, although it's a bit slower than Dektol (1:45 vs. 1:15 for the papers I use).