I think the "opening up" thing depends more on the build than necessarily on the wood.
The only acoustic guitar I ever had that I could say with conviction "opened up" was a cedar-top Seagull S6. For the first three to six months I owned that guitar it literally got better every time I picked it up. I've never had one open up that obviously before or since. By contrast, my Taylor guitar (spruce) that I've had for more than a decade and that has been played far more than that S6 hasn't changed a speck from the day it was new (not that I can tell, anyway). So, if the Taylor opened up at all it did so very slowly - of course, it was an amazingly good guitar to begin with while the Seagull started out just about average for a solid-top guitar.
John