I've already got 23 Hz at -3dB, so compared to just adding more sub 1500s this would be a step backwards for more money. I'm sure the pa 150 is a technically better sub, but other than a 5dB hump at the room mode (which would be an issue regardless of the sub) I'm pretty much +-3dB across the low end. I'm definitely not okay with 30hz. If 30hz was acceptable I might as well just use 3-4 smaller subs and get a more even response across the room. As long as I can get to 25hz, that's good enough for me.
While I agree and understand saving up an dropping a grand on a sub that will not only hit 20hz but will also hit the spl requirements listed above is the best idea, I would be sleeping on the couch if my wife discovered the cost.
I suppose I could diy a couple 15" HO subs, but I've got to find the time between working a ton and home life, I'm also somewhat mechanically challenged.