Well, I tried it this time. Rehydrated a pack of US-05 in the Fermentis-recommended 80F water for a while (I know, sounds cool to me too, but I decided to do it their way for a first try), then pitched it. Next morning, the airlock was burbling happily. Usually, I spend the day after brewing anxiety-ridden because I didn't seem much yeast activity before leaving for school.
There's more than one thing changed with this batch vs the previous APA I did, so I don't know what I'll be able to attribute specifically to the rehydrated pitch. (Need to try new things vs need to control experiments -- Argh!) But the peace of mind at seeing such obvious fermentation alone is reason to keep doing it.