I'm not a professional logger, but I am a forestry student and the president of the schools logging team. Our team has a couple of chainsaws, from husky's, poulans, and stihls. The majority of our saws are professional series stihls, mostly because stihl sponsors collegiate logging sports, and we acquire most of our saws from competitions.
We have stihls ranging from a 021 that we use to practice some events, to an 072 that is just humongous and used mostly for show than anything else. We generally take around 4-8 saws with us on given work weekends, depending on the number of people in attendance.
After using pro series saws I cannot stand to use the non pro series. The anti fatigue spring mounts on the non-pro saws move around too much on me, and I feel it is a weak point, waiting for failure. I think the pro saws are simpler, and will last much longer than the intro, light use saws.
The anti-kickback chain can be useful if you have no idea what kickback is, but I've never ran a full tank of fuel through a saw with anti kickback so I couldn't tell you for sure. I've used smaller t-handle saws while climbing that had anti-kickback chain, but I can't compare that to a full size saw.
I would not let my friends buy anything but a husky or stihl. The husky's are nice for those extra upper rpm, but stihl sponsors my sport and I find is easier to tear down. If I had my choice I would purchase a husky 372xp (which is now the 575 after emissions bs) then a stihl 440 or 460 pro with nothing shorter than a 28" bar as I dont like bending over very far.
Our team recently won a stihl ms280cs (? not sure on exact model, but has no bar nuts, and some weird tension adjuster, also the throttle safety is a chainbrake as well), we're probably going to sell it, or try to trade it for teh regular 280pro, as the 280cs (?) is just weird and foreign to us. We think there may have been a mixup.
Hope this helps.
Another note, most wildland firefighting crews I have seen, run stihl pro series saws, generally 440's or 460's.
Some bark beetle info that I have researched and been taught, I am sorry I am not a professional forest pathologist, but I can try to offer some quick insight into the Dendroctonus , the beetles will easily kill trees with low vigor. They prefer larger diameter trees as well. So if your forest is very dense, with a lot of old trees of large diameter it's only a matter of time before an epidemic outbreak occurs.
If the trees have higher vigor they will be able to "pitch out" the beetles when they attempt to bore in. Once the beetles bore in, they will lay their eggs, and it's the larvae that kill the tree, as they feast in the sapwood and will slowly girdle the tree right beneath the bark. But once the beetles reach epidemic numbers, it can be difficult for even the healthiest of trees to repel the 1000's of attempted attacks.