Not at the moment they are not. As someone who hammers InDesign, Illustrator and Photoshop CS2 day in and day out (there are features in CS2 standard that I cannot live without now, LivePaint and Inline spell checking come to mind, anchored objects, object styles...) and I found it too sluggish for my liking. It certainly did not compare too well with the PowerBook G4 I was using at the time and most certainly not the Power Mac I'm using now.
Photoshop is already optimised for the G5—and under Rosetta you will not get any of those optimisations as Rosetta only emulates a G4 class processor.
Also if you have not got Adobe CS2 for Mac already, you would need to buy that, and then as I noted almost imperatively have to buy CS3 because of its native Intel support. If however you already own CS2 then this is much less of an issue, as the cost won't be too hard to bear.
I agree on the count of the warranty and condition of the unit—that one has to be judged by the person themselves and hopefully it was pass the test.
if it's an Apple refurb, then the unit is likely to be in excellent condition as Apple checks each one of its refurbs carefully with a soak test before it being sold on.
Maybe I was unfortunate, but the iMac 17" Core Duo I used a few times down at an ad agency wiith Adobe CS2 suite installed on, 1.5GB RAM and the rest of it, just did not do anything for me personally, and reminded me strongly of G4-733 I used at Uni in terms of performance. No it wasn't bad, but as soon as I started wanting to really work those three apps running at the same time, using overprint previews etc., I found myself seeing the progress bar a lot.
But that's my 2c, I don't have Adobe CS to try on it, and Photoshop 7 that I have at home is registered in my name so I couldn't have tried that out if I wanted. (Plus I don't have an earlier version of InDesign and Illustrator 6 will not run on an Intel Mac)
I have no doubts however that CS3 on Intel will be a wonderful experience and leave the G5s lagging somehwhat—that I have no qualms or doubts about; but for CS2, I personally (and i'm sure plenty will disagree) could not use it for the kind of work I do.
Vicky