I've heard both. I don't think it's they blow easily, from what I hear it's just if you slam those subs non-stop they'll distort and blow quickly. I don't have experience with the Kicker L7's but my friend had 2 12" in a Corolla, and after a week, he blew one, and a week or 2 after that he blew the next one.
i went through 3 15" L7's 2006 models blew two on RF1000.1 and the third on a PG15:0.1 1st in 2^ft sealed 2nd & 3rd 3.5^ft@30hz i didnt like them, then i got 2 15" CVR's 3^ft@30hz each on RF amp never hadda prob.
I think it all depends on whether you know what you're doing or not. I had mine on a 2500d, a usa-400 for awhile, and now it's on a 2500.1 and is doing fine so far.
if you dont abuse your subs, they wouldnt blow. its pretty much common sense. take care of what you own and know what your doing with them and you will be fine