We just feel the Panasonic has the edge over the Sony - notably for sound, but also a few other bits and pieces (including ability to play DiVX files - no biggie unless you have discs of downloads, really).
But the Sony is a superb player - hence its five stars - and the added convenience of one remote control to drive both TV and Blu-ray player would be a very reasonable point in its favour for you.
You could also, for example, save some money by buying the Sony over the Pana and put it towards buying the MT30s over the KEFs: that would make more difference to your surround sound (providing you bought a decent AV amp) than the difference between the Sony and Pana Blu-ray players.