Just in case you ever wondered, check this out. I ordered a couple new canon lenses from Amazon to test drive, the 24-70/2.8, and the 24-105/4 IS, and after seeing these shots my mind is made up as to which i am keeping. The fans of the 2.8 will argue that the extra stop will help stop motion, which IS can’t help at all, and you could have never got these shots handheld without IS.
On one hand I think its a marketing ploy to those unfamiliar with how it works, and its something of a money grab. To those who do understand the mechanics its a nice “whistle” but not neccessary.
My expereince with IS is limited to Canons 100-400 L IS. I found IS to be virtually useless and as such largely a waste of money with it. The lenses I’m familiar with all seem to be close to double the price of the non is version. Examples being the 70-200 f2.8 or f2.8 IS and again the 70-200 f4 IS and non IS.
Long story short. On the telephoto lenses “typically” you arent shooting static shots in low light “handheld”. Your on a tripod/monopod or “other” and at other times the shutter speeds being used to “freeze” motion are such that IS is a non factor. Examples here are sports shooters and wildlife shooter, say Birds in Flight etc. Worded another way if Im “tracking a moving subject” my shutter speed in all likely hood would need to be high enough to stop the motion ( 1/1000th or higher). If I was in low light with a long lens Id be on a tripod, IS or no IS.