>>But wondering, would a tweeter's ability to deal with first order also be depended on its sentitivity compared to the woofer? This has nothing to do with it. It's in the construction of the tweeter and materials used, Like Wayne says the cone or dome tweeters seem like they can handle it better, where as you get into compression drivers and ribbons the diaphram materials are so thin it won't take much flexing (from the lower freqs. below the x-over point) they'll rip themselves apart on a first-order.
Bill W.