I'd imagine the tegus / monitors are a much larger threat... omnivorous, more intelligent, better climbers, etc. I'd imagine they could easily wipe out birds (eating them and eggs) lizards, snakes, etc. And, I think they are more cold-tolerant, or at least better at burrowing and finding ways around colder weather. Burms are very susceptible to URIs if not at the right temps, so that probably helps control them. I've read that they are not spreading northward, unlike the tegu and monitors.

I think the bigger overall threat is pollution, habitat destruction, etc. (sugar cane fields anyone?). I think it is in FFW's best interests to also overstate their numbers, etc. as they get more funding for eradication projects based on those numbers.

I do think the methods they used in this scenario are very interesting. I'd like to see USFW put as much effort into eradicating feral cats... But that won't happen because people would freak out if they started killing off strays. Don't get me wrong, I own a cat and love them (mine is indoors only) but they crush the local ecosystems they are in and unlike snakes, can survive cold quite well. I've read that feral cats kill an average of one native bird a day and that they will kill / hunt even when full. Same goes for "outdoor" cats that people own.