I generally refrain from anecdotal evidence as a means of offering proof, especially when there is empirical data to show it.
But......
Yes, I have done both and noticed a substantial improvement in my beers. When I first started brewing, I never rehydrated. I made beer that was good; very drinkable and enjoyable. When I started learning about rehydrating, I tried it and was blown away by how such a small step could improve my beer. Example: I recently remade a pale ale that was one of my first recipes, and the first time I made it I didn't rehydrate. It was good the first time, but it was great this most recent time. The yeast had a more pronounced flavor in the first batch, which is not at all what I was going for in an APA. Usually you use 05 because you don't want a pronounced yeast profile. The way to achieve that consistently is by rehydrating, pitching the right number of cells, and controlling fermentation temps.
I've remade plenty of my early recipes, and they all taste better when I add rehydrated yeast, but that APA was the most improved.
There are plenty of reasons that yeast will produce flavor compounds, though, and those batches were years apart so it can be very correctly argued that extenuating or unknown circumstances could be the reason for the difference. Further, no one here can say they know my ability to control those conditions. That is where anecdotes break down, and why we should put some stock in what the "whitecoats" tell us, especially when what they say is in agreement with so many other anecdotes from other brewers.
