I did two rolls of TriX400 120 last night without a presoak. Then I came to APUG between rolls to do a bit of research on the purple tint to the negatives. I found a post that mentioned presoaking, so I tried it. That initial dump of water came out navy blue. I finished developing as normal, and those negatives came out exactly like the ones that did not have a presoak. My ignorant eye can't tell the difference, and I've now forgotten which roll was presoaked.