I guess you have to ask yourself if not having to haul a tripod all over a golf course all day long is worth $500 to you. I've got a Canon IS 28-135 lens and the IS really makes a difference. It takes a little getting used to, but in that enviornment I'd say it was WELL worth the money.

I normally get at least two extra stops with my 28-135 before I need to use a tripod, so I would say it is worth it. I also have a 75-300 IS, and I have taken handheld shots of the moon with the thing.

-EdT.

I own a 70-200mm f/2.8 without the IS.
This is a great lens on a tripod.
If I had to do it over again I would go with the IS.

I bought the 70-200 f/4...sold it for the f/2.8 non IS...sold it for the f/2.8 IS...should have saved some money in the long run and just bought the 70-200 f/2.8 IS to start with...when it comes to that lens..they can have it when they pry it from my cold dead hands..best I have ever owned...my 24-70 2.8L is a good one too, but not quite the 70-200...For what it's worth, after owning all three, if I was to go without the IS id save the money and get the 70-200 f/4..it's as sharp, alot lighter, and if you dont do alot of low light indoor work it's just as good if not a bit better than the 2.8 non IS
George