@ AcutancePhotography: It is heavy, but barely more than my Canon 70-200 II. For backpacking, I would prefer it (and maybe a 1.4 TC) as a tele and macro. Otherwise, I would be carrying my Canon 70-200 and Canon 100 macro. Plus, I would have to change lenses as needed, thereby missing shots.
@ drjlo: I have used LIVE VIEW AF a little and it is slow but accurate.