the DD 9500 is about the most reliable sub you will ever find. I've been around alot of them back when I competed and I've seen single 9515's take as much as 18k watts for a burp and survive it.

All i know about the BTL is what I have read about them. From what I have gathered they are a comp sub, not really a street beater.

Oh and I plan on using DD in my next install in my truck. probably 4 3512's with 6kw.