I've used the suitcase models as stage monitors, but never tried them for HiFi.
They were all over the place (Los Angeles) in the late 70's for approx. $20 pair (junk shops up/down WesternAve in East Hollywood - mainly).
All had ribbed cones, but the magnet shapes varied a lot.
I'd guess that they easily made 8K-9K HZ.
Has a few pairs with large cone tweeters, but they either didn't work or sounded bad.
In hindsight I should have tried replacing the tweeter cap.
DeKay