Klipsch continues to develop and improve their speakers over time, but the simple fact is that they have made fantastic products for a long, long time. I have a pair of KG 5.5's that I purchased in 1997 or so, and they are fantastic. I recently upgraded to a Denon AVR-3805, and my DVD connections went from analog to toslink. I was simply astonished at how good these speakers sound now.
You can probably go "up the line" and get higher end speakers by going used, and that might be a great option for you.
Sorry this isn't quantitative, but I hope it is of some help.
Joel