KeithPJ, just to put another opinion out there, because it seems my personal exeperience is very different from yours:
You say: "iOS 5.0.1 is too bloated to run properly on a 3GS - it needs the extra capability of the iPhone 4S."
My experience: iOS5 runs just fine on 3GS with no slowdowns - just occasionally maybe when there are too many background apps stacked up (possibly a bug in background memory maagement, which should be easily fixed, but really isn't a big deal anyhow).
You say: "the "upgrade" to 5.0.1 should never have been offered to 3GS users. Apple probably knew that. We may have missed a couple of new features, but we'd have had functional devices."
My experience: I'm delighted that I didn't have to do a hardware upgrade in order to acess all the new features, especially iCloud.
I know that some people in some circumstances are experiencing performance issues with iOS5 on 3GS and I don't mean to make light of that. I just think that the stridency of the complaints need balance with a voice for the silent majority who are perfectly happy with the iOS5-3GS pairing.