Insane? I think not! How many of you have spent $5 to $10K for anything in your audio system? LOTS of us, I'd guess.
I heard this thing in Denver, and FINALLY I'm justified in using the superlatives others toss about to describe, say, differences in $1000/M IC cable or home-AC duplex power outlets. This thing is simply awesome, jaw-dropping, fabulous, etc. I could hear tones to about 16Hz, but below that, its output is felt. At 2Hz it was oscillating the room door about 2" peak-to-peak!
Yes is does require an adjacent space. Yes it is expensive, but many companies have subwoofers priced well up into the many-thousands of dollars--the 4-driver Genelec raved about in the SW survey published by the now-defunct 'Stereophile AV Guide' (?) is priced at $12K.
Insane? Not at all. Self-indulgent? You betcha!
.