I have an intolerance for unfermented soy, but my mother's deep-fried fried lemongrass tofu in bún? Don't care. I gladly take the consequences for enjoying that bowl. :D And that's another beautiful thing about bún: swap out ingredients, use leftovers, go with what's seasonally available.

I recently only had wide ho fun noodles available. That was a pleasant variation with an enjoyable tooth to the noodles. I wouldn't necessarily seek it out, but it was a fun experiment in using what I had at hand.