Something to note is that it might be that leghemoglobin (the I-can't-believe-it's-not-heme thing they use) might cause some, uh, adverse reactions in some people. I went to a place that had the v1.0 burgers (somewhere in SF, can't remember where) and I and a couple of colleagues tried one. Me and one guy got diarrhea afterwards, and it turned out that he'd actually had the same happen the first time he tried one (he originally chalked it up to something dodgy he ate before/after, not the burger.) I did find some anecdotal accounts of the same happening to other people, but didn't dig any further.
And I mean it's not like I was like primed to expect something horrible, or stomach upsets or anything. I've been a vegan for quite a while so I don't get the "eek there's no meat in this, it must be disgusting" reaction that some men seem prone to. It's still a protein, so it's always possible it can cause adverse reactions in some people