Martin logan subs any comments?

I have owned the depth sub from martin logan for under a year and am happy, but wondering what others have found when comparing other subs to this one?
Something I learned in this crazy hobby is -- I don't know how much better it can get till I upgrade with the right stuff. Is the JL audio stuff that much better to justify making an upgrade?
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Get rid of the depth, there are subs that destroy it at the SAME price point. Doint buy into name brand. SVS alone is MORE musical, and the bass extension range and loudness will destroy it!

I had the logan descent, and my svs ultra/2 for $1k less new was better in every aspect!!!