To expand on what cudamark says: Not sure of the technical ramifications of combining a pulse and a standard VLF together. I mean, the innards, coils, etc.... may be diametrically opposed. But assume for the moment that someone (Whites?) found a way to do that. So that, in theory, a person can effortlessly flip a switch and have a beach pulse on minute. Then flip the switch the other way, and have a standard VLF (for land where he intends to pass iron, or foil, etc....).
The reason why this is highly suspect, is that such attempts at hybrids for nugget vs coin machines (like the 705 for instance) have inherent weaknesses. They aren't the best nugget machines, nor are they the best coin machines. By far.
The reason is: That the GOALS of each venue, when you think of it, are opposed to each other. The coin/relic hunter DOESN'T want the bells of Notre Dame to ring on every pinhead, nail, straight-pin, etc... But the nugget hunter WANTS to hear all those tttteeennnssssy things. So to make a machine that can switch back and forth between each type hunting, is no easy task apparently. Since they are usually built from-the-ground up, for the specific tasks in mind. Thus you get compromises on each end, if you try to make a hybrid.
So I'm not sure what the technical implications (coil types , etc...) of pulse vs vlf is, but ... odds are, it'll have issues. Also remember: Nothing technologically would be gained. We ALREADY have pulse machine abilities. We ALREADY have vlf machines. So what's the point ? Other than a "do-all" single machine so you don't have to keep each kind in your truck. Or perhaps the novelty of being able to sample a target in each mode for tell-tale audio ID clues.