I have to agree with previous speaker about that New Guinea is not THAT dangerous, only place you should watch is Port Moresby and a few other large cities, where tourists easily can be robbed.
I would say that the rest of the island is fairly secure today, most gerillas on the island is gone since many years, very sceptical about that widespread cannibalism still occur here, newspapers here still describe it as a large "culture" of Papua New Guinea and that it still is widespread, but they never seems to provide any concrete info or evidence about it, but as I said Iam very sceptical about the whole thing, maybe a few remote tribes still eat each other, but you cant expect to meet any cannibals while bird watching.
The road network is still very bad in most of the island, but the eastern half is an exception here has the government put down a lot of money to make new and larger roads, which is both good and bad, I prefer the remote, untouched and inaccessibly New Guinea, and if you think that its hard to get to some areas, it some thing that characters the birding of New Guinea, its both god bird watching but also a adventure and it often takes days to get to the best birding sites, but that the charm with it, if you wanted easy birding (such in east Africa) you have chosen the wrong place to go.
Papuan birder