I.S. lens question

First, even though this is only my 2nd post, I've used this forum for several years and all of you have guided me from a S200, to a G5, and to my current 300d. I'm contemplating my first I.S. lens purchase (17 - 85 ). I have 3 questions that I hope haven't already been beaten to death in previous threads.

1. With I.S. , do you turn it on and forget it, or only as lighting conditions dictate?

2. Since I.S. optics are more complex than those on standard lenses, are there any reliability/durability issues?

3. Is it much of an extra battery drain?

1. Personally, I leave it on all the time except when using a tripod - the 17-85 does not have automatic tripod detection.

2. IS can fail and I have heard of some failures, notably on the 100-400 but I would say it is a pretty reliable system on the whole, however if it were to fail on a lens which was out of warranty I would guess it would be pretty expensive to repair.

The 17-85 is a nice lens, you'll enjoy using it.

1. I leave it on, can't hurt, unless it's on a tripod.
2.There are no liability issues/durability problems, but I do treat them better than standard becasue of the exrtra technology such as wires, chip etc.
3.Is it a battery drain?, yes, but it depeds what your shooting temperature range is, I think it takes 15-% Battery, don't qoute me on that . Obviously if it's 32F out, it will drain faster.
I've used the 70-200is and 24-135mm IS on the Mark 2 and 20D, I really didn't notice anything...but I'm one who turns off the camera as soon as I take the picture to conserve.

1) leave it on all the time
2) has no problem with it thus far
3) i think it does drain some battery, you need power to power the IS

I leave "IS" on all the time when not shooting fast action with my older then dirt 75-300mm IS-USM, that's how I would likely use the 17-85 IS too unless it has mode-2 for panning.

I have the old shool 75-300 f4-5.6 USM IS lens. I don't get much use from it, but when I do use it, I seem to be using the long end of the lens anyway, therefore, I find the IS very useful. On the shorter end of the lens, I've handheld it with the IS off, if the light is good.

It's been a great lens to have when I've needed it, I'm just not sure that I need it often enough to keep it anymore!

I haven't noticed any significant drain on the battery, and I imagine the 17-85 would be better due to the fact that it's newer (Improved technology?) and likely smaller elements to move. I may be way off base there, though.