A lot of guys at AVSforum have reported a substantial upgrade from a PB13 to a Submersive, and since it isn't much more $, why not. The ED A7-450 probably has more max clean output than both of them, and is cheaper than both, so if the size and weight can be handled, that would be a good alternative too. Another good option would be the deftech Trinity, it can be had for less than $2k if you look around. The PB13 is a great sub for sure, but there are some very good alternatives, especially if you don't have to worry about WAF as much.