Sadly that's what people like to do. It's like with all the comparisons between Catherine and Diana - or Diana and Sarah for that matter. I think in a way Edward was smart to not marry until after the failure of his brothers' marriages - Sophie doesn't seem to have the same amount of pressure placed on her as Diana and Sarah had to deal with, or as Catherine gets.
As long as they exist, really, Harry's girlfriends and future wife will be compared to Chelsy, Diana, Catherine, and really probably any other long term girlfriend that appears between Chelsy and the future wife. The future wife might also get compared to Sophie (in that their roles as the wife of the younger son of the (future) monarch presumably will be similar), while his exes (especially Chelsy) will get Camilla comparisons. Catherine, meanwhile, can look forward to a continuation of the Diana comparisons, then eventually comparisons to HM, Prince Philip, and QEQM. William will be compared to his mother, father and his grandmother, Harry to his mother and uncles. It's not really a fun outlook for them....
