Well, here's one man's opinion:

Grain is primarily determined by the film you shoot.  Shoot 3200--you get
grain.

Having said that you can somewhat reduce grain by choice of developer, you
already have chosen D-76, not a bad choice, it is some what finer grained
than, for example, HC-110.  The trade-off is longer processing times.

It's been my experience that agitation, etc. have a much smaller effect on
grain formation than film and developer choice.  Total wet time is reputed
to affect how much grain clumping you can get--mind you--I've never tested
this assumption, but it's in the folklore.

The Massive developer chart  http://www.digitaltruth.com/devchart.html
suggests 14 minutes for straight D-76 at 68F/20C.  I don't think I'd try
1+1!--it's not in the chart--I imagine the developing times would be pretty
long and there might be a fall off in developer action.  (Most developers
have slightly finer grained properties at lower dilution's, D-76 straight
has more solvent action than at 1:1 with slightly lower accutance--which
will also reduce the appearance of graininess.)

D-76 is just fine for TMax 100 and 400.  (Having said that, to be completely
honest, I don't use D-76 anymore, I find it too much of a hassle to mix, I
use TMax developer and HC-110.)

--
darkroommike

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