They have bump stops, they were popular, and 20-250 + - 3 db, 250 watt plate. They are more of a bass bin (wider range) 250 down. The kits had a 12" HE driver. I just googled the things.. Had a pretty good rep... The thing with a down firing driver is gravity, it takes its toll. Even passive radiators take a greater beating on the bottom.. The trick was to make it light enough to return quickly, but tough enough to hold up (Weight of the return single/double spring + the weight of the cone and mass for tuning..
Add the weight of a good voice coil.... Yikes.. it has to be well designed... to be fast / dampened and hold up... Bottom firing drivers has one more issue... The surrounds are more prone to moisture, dust, ect.. They just don't last as long.. Just something to think about.. No bad stuff I read, Good reviews. BUT that was 2013... TIME..... A good inspection is in order at least...
Regards