The 750 and the Sebenza are mechanically similar, and use similar materials, but are two quite different knives. If nothing else, the blade shapes are definitely two different visions of what is a good versatile blade for a folding knife. The 750's blade is not a substitute for the Sebenza's blade, and the Sebenza is probably not the first choice for a customer who likes a saber-ground recurve blade.
If you look at the detail pictures I took in the link posted above, you'll see a bunch of little manufacturing details on the Sebenza that are not on the Benchmade. If an operation like Benchmade tried to add all those details, the price would probably double, though economies of scale might bring the street price down to maybe $250 or so, as opposed to $325 with a full size Sebenza.
The various corners on the Sebenza that are rounded or beveled, where the 750 has a 90 degree angle, might make my hands prefer the Sebenza after a few hours of working with it. For a few minutes of usage here and there, it probably doesn't matter much.
If you're looking for a rock-solid integral lock, with good steel and titanium, the 750 will fill the need. And remember, for perspective, that there are a lot of people out there who think that a Spyderco Delica is an expensive knife, beyond their perceived point of diminishing returns.