This is definately a fuzzy area. I had the luxury of 125 watts pounding while I was at work for 9 hours(can you say single). When I got home it was good to go. The validity or break in is argued, but when I got my Delta 15's thumping the cone sounded like styrofoam cups. After the torture test(still only half rated power for Theater 4's) I thumped them and got a tight dry thud that sounded way deeper. With soft jazz at mild levels it could be a while. I choose this example for ease of demonstration, but the tweeter should respond to break in like the woofer, give or take some for difference in construction and materials. It's like good new shoes. It's work just walking, but after you wear them some they are the most comfy things you own. Just play them a lot. Pick a disc with wide range and play it every weekend. You'll know. Let us know what you think after you move them around some, and they relax a little. I'm not saying you will retire the mags, That's to your taste, but I will bet you find a great setup for the Pi's and really enjoy them.While reading one of the other posts I thought I should add that I have had mine all over this house and they are not hard to place. Meaning they do a good job in some awful situations. As for getting them to really gel like well set up Maggies (and I do like Mags and Acoustat too) I find that up against the wall with toe in crossing well in front of you will make you grin. They will never act like Maggies and your mileage may vary, but they sound bigger and more lush that way, and placement is free. Have fun.
Thomas