If you can cast ok, a longer rod should make a difference, in theory. Don't know about the Leeda Assassin personally but a lot of manufacturers are going down the continental model rods. That is a rod that is a bit softer in an all through action, 15 or 16 feet in length and made for fixed spool reels. This means you should be able to compress it easier and the extra length gives you a theoretical faster tip speed. Beware though, a longer rod can feel cumbersome and takes a bit of getting used to.
On the other hand Sonik's SK4 beach rod is 16 foot long and is softish in the tip section only.