Yes, they are colubrids.
The implications if you get bitten are severe. The boomslang (which possesses the same venom) has developed rear fangs for feeding on birds, which essentially means they have long teeth to penetrate the feathers. The Jacksons tree snake is a more general feeder (ie natures dustbin) and hasn't developed the teeth the boomslang have so doesn't have the penetration ability.
This isn't to say they have a rubbish delivery system, it just isnt as specialised as the boomslang.
If you get a "good" bite you can expect to start bleeding from every orifice (ie. eyes, mouth, nose, ears and the lower points). I don't know if there have been recorded deaths but there could have well have been fatalities that have been put down to the boomslang as they do look the same to the uneducated. I have also heard rumours of paralysis occuring after a severe bite (not permanent though)
When compairing to the likes of a FWC, a bite from a FWC is nothing.
These snakes were very lucky to miss the DWAL, i would certainly place them as far more "dangerous" than a mangrove which is on the DWAL.
