Hi ctribble...
I recently auditioned the 250P and ended up choosing a Velodyne over it...
Model here is Australia I purchased was a CHT-10R.
I think the equivalent (USA & Canada – 110volt) is the DLS-3750R.
Excluding specs, I made up a DVD that had examples of some decent bass on it that I took from store to store or had the benefit of trying 1/2 a dozen different subs with. Nemo - whale scene, U571 - depth charges, Gone in 60 secs - Eleanor (love the rumble of a big V8 <grins>), Matrix - Courtyard fight, Gothica - very start plus a few others.
From the reading and reviews that I had done on the JBL 250P, my mind was near made up without hearing the sub in real life.
I wont profess to being an Audiophile, though I feel my ear is getting better at picking up detail, I’m not afraid to ask questions in a store, and to question how they come to certain conclusions (is "Because" an answer?), and certainly know when a speaker is struggling to hold, and or deliver.
Without rambling, I found the 250P wasn’t as tight in reproducing bass at higher volumes in I’m guessing the 35-50Hz range (see Eagles Hotel California from the DTS demo most Yamaha dealers have), and with HT, didn’t energise the room as well as many of its peers.
For HT, I give the factor of trouser movement against the hairs on my legs a fair bit of weight - this I’m afraid in the same conditions, volume, fresh YPAO (on a Yamaha amp), as competitors such as my final choice I didn’t find the 250P to deliver. <shrugs>
Best of luck with your research.
A