I haven't rehydrated dry yeast since '96... have used SO4, S23 and Nottingham commercially without rehydration and saw zero difference in the finished product. I don't remember where the thread was, but someone had a vid up where they did a side-by-side comparison of dry yeast; rehydrated vs dry, and aerated vs non aerated. The progress of the fermentation was slightly different, but in the end they all ended up at the same place.
I put my yeast in the ferm prior to knockout... whether that means dumping int into a unitank in a brewery, or in the bottom of a bucket, and running the wort in after. My beers have an average lag time of about 6 hours from knockout to signs of active ferment. Works just fine for me... good starts, clean beer and one less possible source of infection.
"Why did you.... what was the point of... how drunk were you when you decided this was a good idea?" - DMartin