You could but frankly I've read dodgy things about hydrogenated veggie fats. I think you are better off with beef suet, from the health point of view.
Actually, a lot of the suet comes out into the water during cooking, which is why suet pastry is always spongy, i.e. full of holes. So it's not really fatty to eat at all.
I've read up about this: seems the key thing with suet pastry is the fat has a high melting point, so the pastry is already starting to set when the fat melts. Hence it runs out, leaving a porous, flexible structure behind. When you use butter, as in normal pastry, it melts in at the start, making a far greasier final pastry, but which goes crisp. So maybe suet is not as bad for you as it seems.