I suspect that tree climbing researchers have historically had an extremely wide range of skill and ethics, depending on how they entered the activity. Scientists are often likely to view climbing as simply one of many possible routes to \"access\" the canopy, and they will be more or less thorough in finding out how to do it right.
Joe has definitely seen some pretty awful practice. So have I, both in my own doings (see below), in internet published photos of canopy researchers (people apparently working well above their TIP), and in stories I have heard about some researchers at Itasca State Park around here (climbing living trees with spikes!!).
Early in my canopy research about 4-5 years ago (measuring light in different locations in and above canopies with undergrads), we were using tree ladders and deer stands to work 30-40 feet off the ground. What we did was, frankly, pretty scary, and I still get the willies when I think about it. It was worrying about this that got me into rope access methods and rec tree climbing in the first place, and now I climb at least as much for fun as for research. The work I was doing on hydrologic stress in 120-140 foot white pines last summer and fall with a couple of grad students would have been well beyond my technical reach as recently as 2 years ago, and it was largely practice with rec climbing that enabled it.
None of this can possibly translate into a reliable generalization about research climbers; the worst of them are dangerous to themselves, their students, and their trees; and the best are exemplary on all fronts.
MEA, are you going to be at the ESA meetings in Milwaukee this year? I caught your talk at San Jose last year and liked it a lot.