So I popped on this cab today after looking at it for weeks. Brought my amp in and checked out and it sounded good, no rattles or farting out, at least at halfway on my GK 700RBII. Ended up getting it for 200 out the door. Brought it home it really sounds killer, BIG lows. I pulled the speaker out to see what the heck had been put in there and it is an Eminence Kilomax Pro. I know there is a lot of calculations into what speaker will work in what box and there are programs that some of you have to figure this for you.
So I guess the question I have is am I better off keeping this speaker in here or selling it and replacing with a Kappalite 3015LF before prices get to crazy? Other than the lighter weight what is there going to be a real gain made in switching the 2?
That's basically a TL606 box. There are a lot of good drop-in options for that cab. I don't know if the 3015LF is one of them. Ask one of our speaker gurus.

Here's a brief thread on that: http://www.talkbass.com/forum/f15/kappa-3015lf-tl-606-cab-621144/