I have been using Pentax 35mm SLR and DSLR for a long time when i bought my K20D, i didn’t care much about the Shake Reduction (SR) system. The advantage of in-body image stabilization is that all lenses are stabilized, even my old Takumar (M42) lenses ! I learned to like SR by using it more and more, sure i prefer to use a sturdy tripod as often as i can but there is time when a tripod is not practical.
I do a lot of frog photography, the lens i use the most often is my DFA 100mm Macro WR handheld and i crawl on the ground to have a frog eye’s view, so SR is handy for that kind of shots. If my shutter speed is very slow i use a ziploc bag filled with sand to stabilize the lens to help SR, i was able to shoot at very slow shutter speeds with this technique. I also use lenses from my 14mm up to my 100mm Macro lens for taking frog shots handheld. I don’t use SR often with my 400mm lens (about 8.3 pounds of glass and metal), i prefer to use it on a tripod.
I think it’s even useful with wide angle lenses when i want to go very low to the ground when i want to show frogs, mushrooms and flowers in their habitat. I certainly got photos that i wouldn’t have been able to get with a tripod because i needed to get in a position where it would have been impossible to set-up a tripod.
The photo of this young American toad was taken with a Pentax K20D, DFA 100mm Macro WR, ISO 800, 1/5 sec. at f/9.0 handheld with SR and braced on a small bean bag.