Hi, yes, I have seen them, been listed for ages. Doubt they are the world's most popular pulse generator, in fact do they still make general purpose pulse generators? I got a service manual from the late lamented Manuala Plus some months ago. Like the actual generator, postage was greater than the value of the goods!
Looking further, the problem seems to be that pulse generators are made for logic use, not analogue, so having a pulse that goes +ve and -ve isn't needed for logic, just blows it up. The reason why the feature was removed from the B version.
Perhaps I am needlessly complicating things but how would you combine two outputs to make a bipolar one with, say, 10V drive into 50 ohms?