Originally Posted by benj
I would be interested though if any academic literature has addressed the topic... I may have to go do a search now
Plenty has been done. See the Dry Yeast FAQ sticky and go through the "Suggested Reading" portion at the bottom of the first post, there is lots of good info there. Sean Terrill did cell counts with US-05 after rehydrating in warm & cold water as well as warm & cold wort. Drs. Chris White and Clayton Cone both recommend rehydrating (White Labs and Danstar, respectively) in order to prevent losing 50% of the yeast cells to osmotic shock. Dry yeast manufacturers advise rehydrating. It's been covered.