I'm not a veggie but I've always thought if I did go that way, black pudding would be the last thing I could give up. (unless I found out they were made like foie gras or something).
I do think stuff like veggie haggis, sausages & black pudding makes more sense than Quorn steaks etc, as its all about the seasoning & the recipe.
I mean as a meat-eater, I'd quite happily choose a veggie haggis or veggie sausages because I like the taste, but if I wanted a steak I'd just eat a real one or not at all.
Though its interesting that the products I've mentioned are all offal-y type things, so if one was to try & be an 'ethical-meat-eater' presumably it would be ones duty to make use of all the offal once you'd killed your animal?