Hi,
I exclusively use DD-23, since a few years now, for simple reasons : the negs it gives me perfectly suit me, and I've never used such an easy and economical developer. You can develop every negs of every sensibility together, with always the same times. After having tried Rodinal, ID11, pyro... I found it is no worse than any of the previous ones (actually sometimes better) and that it avoids me headaches and losing some time.
I use as a basis one of the formulas given in the darkroom cookbook :
A bath : 7.5g metol + 100g sodium sulfite per liter
B bath : 10g borax per liter
I've tried reducing the sulfite amount in bath A as suggested, but I find it makes the grain grow too much without improving the acutance enough. I prefer adding 4g of ascorbic acid, as suggested elsewhere in this forum I think. I've not done a lot films with this combination, but it seems the grain is crisper and finer. I've also tried adding salt in bath B to reduce the grain, but I've noticed no change. Maybe because I've used table salt, and not laboratory grade salt?
As for the times, I proceed as in the darkroom cookbook : pre-soak, 5 minutes in bath A with 30 sec of agitation, then 15 sec of agitation every minute, the film is then placed directly in bath B for 5 minutes, with 5 seconds of agitation every minute, then stop, fix, wash.
I keep the A bath for 20 films apprixomately, and mix a fresh B bath every time.
To be honest, I've never had underdeveloped or flat negs, but I'm always on the "slightly overexposed" side when I shoot, never hesitating to add one stop. But when a neg is really too overexposed, it comes out black all the same, but I feel the latitude is far greater than with other developers. However, I've tried pushing underexposed films by increasing the times in A&B baths, but it was catastrophic, the neg being way too soft to be printed.
I hope this helps,
Skander